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A029544 Near Cullen numbers: k such that (k+1)*2^k + 1 is prime. 4
0, 1, 2, 5, 6, 13, 26, 65, 66, 86, 114, 133, 186, 294, 445, 866, 1325, 1478, 1823, 2765, 7553, 7943, 10178, 20960, 20964, 21337, 26562, 85374, 96749, 247038 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
COMMENTS
Primes in the sequence are 2, 5, 13, 1823, 96749, ... - R. J. Mathar, Oct 15 2011
We can write (k+1)*2^k + 1 = {(k+1)/2}*4^{(k+1)/2} + 1, and when k is odd, this takes the form of a generalized Cullen prime (base 4). These are listed in A007646. In other words, {2*A007646 - 1} gives all the odd terms of this sequence. - Jeppe Stig Nielsen, Oct 16 2019
LINKS
PROG
(PARI) isok(n) = isprime((n+1)*2^n+1); \\ Michel Marcus, Nov 09 2013
CROSSREFS
Sequence in context: A154365 A247959 A243799 * A058668 A271640 A180744
KEYWORD
nonn,more
AUTHOR
EXTENSIONS
Corrected and extended by Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008
STATUS
approved

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Last modified March 29 08:13 EDT 2024. Contains 371265 sequences. (Running on oeis4.)