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Search: a007088 -id:a007088
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Odd positive integers in base 2 (bisection of A007088).
+20
7
1, 11, 101, 111, 1001, 1011, 1101, 1111, 10001, 10011, 10101, 10111, 11001, 11011, 11101, 11111, 100001, 100011, 100101, 100111, 101001, 101011, 101101, 101111, 110001, 110011, 110101, 110111, 111001, 111011, 111101, 111111, 1000001
OFFSET
1,2
COMMENTS
List of binary vectors that begin and end with 1.
MAPLE
seq(convert(2*n-1, binary), n=1..37); # Emeric Deutsch, Dec 15 2004
MATHEMATICA
FromDigits/@IntegerDigits[Range[1, 71, 2], 2] (* Harvey P. Dale, Apr 05 2019 *)
PROG
(PARI) a(n) = fromdigits(binary(2*n-1), 10); \\ Michel Marcus, Apr 23 2020
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
N. J. A. Sloane, Nov 19 2004
EXTENSIONS
More terms from Emeric Deutsch, Dec 15 2004
STATUS
approved
a(n) = A007088(A122229(n)).
+20
7
0, 10, 1100, 111000, 11100100, 1110011000, 111001100100, 11100110011000, 1110011001100100, 111001100110011000, 11100110011001100100, 1110011001100110011000, 111001100110011001100100
OFFSET
0,2
KEYWORD
nonn,base
AUTHOR
Antti Karttunen, Sep 14 2006
STATUS
approved
a(n) = A007088(A122232(n)).
+20
7
101010, 11010100, 1111100000, 111100100100, 11110001011000, 1111110010000100, 111101100010011000, 11110001101100100100, 1111101011000110000100, 111101100110001100010100
OFFSET
1,1
KEYWORD
nonn,base
AUTHOR
Antti Karttunen, Sep 14 2006
STATUS
approved
a(n) = A007088(A122242(n)).
+20
7
101010, 11110000, 1110010100, 111010100100, 11101001110000, 1111001010011000, 111100100101110000, 11101100101001011000, 1110110010011011100000, 111100111001000110110000
OFFSET
1,1
KEYWORD
nonn,base
AUTHOR
Antti Karttunen, Sep 14 2006
STATUS
approved
a(n) = A007088(A122245(n)).
+20
7
101100, 11101000, 1110011000, 111100100100, 11101001011000, 1110110010011000, 111100100110110000, 11110011010001011000, 1110110010010110101000, 111011001110000110110000
OFFSET
1,1
KEYWORD
nonn,base
AUTHOR
Antti Karttunen, Sep 14 2006
STATUS
approved
In the sequence A007088 of binary representations of n, delete the 1st, 3rd, 5th, 7th, 9th etc occurrence of 0 and 1. Rewrite the bits left over in base 10.
+20
7
2, 1, 0, 1, 2, 3, 0, 2, 2, 5, 2, 1, 6, 3, 0, 2, 4, 5, 2, 1, 5, 3, 2, 2, 5, 5, 2, 3, 6, 7, 0, 4, 4, 9, 2, 1, 10, 3, 4, 2, 10, 5, 2, 5, 5, 11, 4, 2, 10, 5, 2, 5, 5, 11, 2, 6, 6, 13, 6, 3, 14, 7, 0, 4, 8, 9, 2, 1, 9, 3, 2, 2, 9, 5, 2, 5, 10, 11, 4
OFFSET
0,1
COMMENTS
Deleting the odd occurrences of 0 and the even occurrences of 1, we get the same sequence apart from the initial 2 replaced by 1 and 0.
EXAMPLE
Numbers in base 2: 0, 1, 10, 11, 100, 101, 110, 111, 1000, .... Delete odd occurrences of 0 (replaced by ~): ~, 1, 10, 11, 1~0, 1~1, 110, 111, 1~0~ Delete odd occurrences of 1 (replaced by ~): ~, ~, 10, ~1, ~~0, 1~~, 1~0, 1~1, ~~0~.
The pieces left are 10, 1, 0, 1, 10, 11, 0, ... which is in base 10: 2, 1, 0, 1, 2, 3, 0, ....
MAPLE
n1 := 1 ; n0 := 1 ;
for n from 0 to 80 do
if n = 0 then b := [0] ; else b := convert(n, base, 2) ; end if;
for d from nops(b) to 1 by -1 do
if op(d, b) = 0 then
if type(n0, 'odd') then b := subsop(d=NULL, b) ; end if; n0 := n0+1 ;
else
if type(n1, 'odd') then b := subsop(d=NULL, b) ; end if; n1 := n1+1 ;
end if;
end do:
add(2^(i-1)*op(i, b), i=1..nops(b)) ; printf("%d, ", %) ;
end do: # R. J. Mathar, Nov 23 2010
KEYWORD
easy,nonn,base,less
AUTHOR
EXTENSIONS
Sequence extended, keyword:base,less added by R. J. Mathar, Nov 23 2010
STATUS
approved
a(n) = A007088(A122235(n)).
+20
6
101100, 11011000, 1111001000, 111100010100, 11111100000100, 1111001001110000, 111100010111000100, 11111111000010000100, 1111100010011011000100, 111101101001110000100100
OFFSET
1,1
KEYWORD
nonn,base
AUTHOR
Antti Karttunen, Sep 14 2006
STATUS
approved
a(n) = A007088(A122239(n)).
+20
6
110100, 11110000, 1111000100, 111110000100, 11110011000100, 1111110000010100, 111100100111100000, 11110001011100100100, 1111111000101100000100, 111100101001101001110000
OFFSET
1,1
KEYWORD
nonn,base
AUTHOR
Antti Karttunen, Sep 14 2006
STATUS
approved
a(n) = A007088(A080316(n)).
+20
3
0, 1100, 11001100, 11110000, 110011001100, 110011110000, 111111000000, 111100001100, 111100110000, 1100110011001100, 1100110011110000, 1100111111000000, 1100111100001100, 1100111100110000, 1111110000001100
OFFSET
0,2
COMMENTS
Note that here we have totally balanced binary sequences (as in A014486/A063171), 10, 1010, 1100, 101010, 101100, 110010, ..., but with each bit duplicated. Furthermore, the order is a bit different.
KEYWORD
nonn
AUTHOR
Antti Karttunen, Mar 02 2003
STATUS
approved
Even nonnegative integers in base 2 (bisection of A007088).
+20
3
0, 10, 100, 110, 1000, 1010, 1100, 1110, 10000, 10010, 10100, 10110, 11000, 11010, 11100, 11110, 100000, 100010, 100100, 100110, 101000, 101010, 101100, 101110, 110000, 110010, 110100, 110110, 111000, 111010, 111100, 111110, 1000000
OFFSET
0,2
MAPLE
seq(convert(2*n, binary), n=0..37); # Emeric Deutsch, Dec 15 2004
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Nov 19 2004
EXTENSIONS
More terms from Emeric Deutsch, Dec 15 2004
STATUS
approved

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