A134304 - OEIS

A134304

Least k such that k*2^n*(k*2^n-1)-1 and k*2^n*(k*2^n-1)+1 are twin primes.

2, 1, 2, 1, 11, 21, 57, 211, 141, 156, 78, 39, 140, 70, 35, 214, 107, 90, 45, 309, 330, 165, 120, 60, 30, 15, 435, 651, 420, 210, 105, 429, 1143, 576, 288, 144, 72, 36, 18, 9, 116, 58, 29, 2286, 1143, 1638, 819, 1071, 983, 1983

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Table of n, a(n) for n=1..50.

PROG

(PARI) a(n) = {my(k=1); while (!(isprime(p=k*2^n*(k*2^n-1)-1) && isprime(p+2)), k++); k; } \\ Michel Marcus, Sep 17 2019

CROSSREFS

Cf. A134303, A134305.

Sequence in context: A097749 A126906 A179508 * A211096 A134569 A295853

Adjacent sequences: A134301 A134302 A134303 * A134305 A134306 A134307

KEYWORD

nonn

AUTHOR

Pierre CAMI, Oct 19 2007

STATUS

approved