The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A221309

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A221309

Numbers m such that no subset of {m-1, m, m+1} sums up to a prime number.
(history; published version)

#7 by Charles R Greathouse IV at Sat Jul 13 12:04:36 EDT 2013

LINKS

_Reinhard Zumkeller_, , <a href="/A221309/b221309.txt">Table of n, a(n) for n = 1..10000</a>

Discussion

Sat Jul 13

12:04

OEIS Server: https://oeis.org/edit/global/1934

#6 by N. J. A. Sloane at Fri Feb 22 21:39:23 EST 2013

LINKS

_Reinhard Zumkeller, _, <a href="/A221309/b221309.txt">Table of n, a(n) for n = 1..10000</a>

Discussion

Fri Feb 22

21:39

OEIS Server: https://oeis.org/edit/global/1866

#5 by Reinhard Zumkeller at Thu Jan 10 14:02:18 EST 2013

STATUS

editing

approved

#4 by Reinhard Zumkeller at Thu Jan 10 13:04:20 EST 2013

COMMENTS

A117499(a(n)) = 0.

EXAMPLE

a(1) = 25: there are 7 nonempty subsets of {25-1, 25, 25+1}: {24}, {25}, {26}, {24,25}, {24,26}, {25,26} and {24,25,26} with sums and factorizations: 24=3*2^3, 25=5^2, 26=13*2, 49=7^2, 50=5^2*2, 51=17*3 and 75=5^2*3.

PROG

(Haskell)

a221309 n = a221309_list !! (n-1)

a221309_list = map (+ 1) $ elemIndices 0 a117499_list

CROSSREFS

Subsequence of A079364.

#3 by Reinhard Zumkeller at Thu Jan 10 13:02:34 EST 2013

NAME

allocated for Reinhard ZumkellerNumbers m such that no subset of {m-1, m, m+1} sums up to a prime number.

DATA

25, 77, 85, 92, 93, 94, 118, 122, 123, 124, 133, 143, 144, 145, 160, 161, 170, 171, 185, 188, 202, 203, 206, 207, 208, 213, 214, 218, 235, 236, 237, 247, 248, 253, 259, 265, 266, 267, 275, 287, 290, 291, 295, 298, 302, 305, 319, 325, 328, 333, 334, 335, 340

OFFSET

1,1

LINKS

Reinhard Zumkeller, <a href="/A221309/b221309.txt">Table of n, a(n) for n = 1..10000</a>

KEYWORD

allocated

nonn

AUTHOR

Reinhard Zumkeller, Jan 10 2013

STATUS

approved

editing

#2 by Reinhard Zumkeller at Thu Jan 10 08:43:20 EST 2013

KEYWORD

allocating

allocated

#1 by Reinhard Zumkeller at Thu Jan 10 08:43:20 EST 2013

NAME

allocated for Reinhard Zumkeller

KEYWORD

allocating

STATUS

approved