The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A053337

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A053337

a(n) contains n digits (either '6' or '7') and is divisible by 2^n.
(history; published version)

#9 by Ray Chandler at Sat Jun 13 15:06:19 EDT 2020

STATUS

editing

approved

#8 by Ray Chandler at Sat Jun 13 15:06:15 EDT 2020

LINKS

Ray Chandler, <a href="/A053337/b053337.txt">Table of n, a(n) for n = 1..1000</a>

STATUS

approved

editing

#7 by Harvey P. Dale at Sun Jul 10 14:24:34 EDT 2016

STATUS

editing

approved

#6 by Harvey P. Dale at Sun Jul 10 14:24:30 EDT 2016

MATHEMATICA

Table[Select[FromDigits/@Tuples[{6, 7}, n], Divisible[#, 2^IntegerLength[ #]]&], {n, 18}]//Flatten (* Harvey P. Dale, Jul 10 2016 *)

STATUS

approved

editing

#5 by Harvey P. Dale at Sun Jul 10 14:23:24 EDT 2016

STATUS

editing

approved

#4 by Harvey P. Dale at Sun Jul 10 14:23:16 EDT 2016

MATHEMATICA

Table[Select[FromDigits/@Tuples[{6, 7}, n], Divisible[#, 2^IntegerLength[#]]&], {n, 18}]//Flatten (* Harvey P. Dale, Jul 10 2016 *)

STATUS

approved

editing

#3 by Russ Cox at Fri Mar 30 18:51:20 EDT 2012

AUTHOR

_Henry Bottomley (se16(AT)btinternet.com), _, Mar 06 2000

Discussion

Fri Mar 30

18:51

OEIS Server: https://oeis.org/edit/global/247

#2 by N. J. A. Sloane at Fri May 16 03:00:00 EDT 2003

FORMULA

a(n)=a(n-1)+10^(n-1)*(6+[a(n-1)/2^(n-1) mod 2]) i.e. a(n) ends with a(n-1); if (n-1)-th term is divisible by 2^n then nth n-th term begins with a 6, if not then nth n-th term begins with a 7.

KEYWORD

base,nonn,new

AUTHOR

Henry Bottomley (se16@(AT)btinternet.com), Mar 06 2000

#1 by N. J. A. Sloane at Mon May 08 03:00:00 EDT 2000

NAME

a(n) contains n digits (either '6' or '7') and is divisible by 2^n.

DATA

6, 76, 776, 7776, 67776, 667776, 6667776, 66667776, 766667776, 6766667776, 66766667776, 666766667776, 7666766667776, 77666766667776, 777666766667776, 7777666766667776, 77777666766667776, 777777666766667776

OFFSET

1,1

FORMULA

a(n)=a(n-1)+10^(n-1)*(6+[a(n-1)/2^(n-1) mod 2]) i.e. a(n) ends with a(n-1); if (n-1)th term is divisible by 2^n then nth term begins with a 6, if not then nth term begins with a 7.

CROSSREFS

Cf. A023409, A050621, A050622, A035014.

KEYWORD

base,nonn

AUTHOR

Henry Bottomley (se16@btinternet.com), Mar 06 2000

STATUS

approved