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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 of the form n+1 are 2, 3, 7, 67, ... - _Juri-Stephan Gerasimov_, Oct 02 2011

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 members of this sequence. - Jeppe Stig Nielsen, Oct 16 2019

LINKS

Table of n, a(n) for n=1..30.

Steven Harvey, NearCullen and NearWoodall Primes

PROG

(PARI) isok(n) = isprime((n+1)*2^n+1); \\ Michel Marcus, Nov 09 2013

CROSSREFS

Cf. A002064, A007646, A230769.

Sequence in context: A154365 A247959 A243799 * A058668 A271640 A180744

Adjacent sequences:  A029541 A029542 A029543 * A029545 A029546 A029547

KEYWORD

nonn,more

AUTHOR

Henri Lifchitz

EXTENSIONS

Corrected and extended by Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008

STATUS

approved

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Last modified July 13 04:53 EDT 2020. Contains 335673 sequences. (Running on oeis4.)