A074884 For a prime p, let k(p) be the least k such that 2kp+1 is prime. Sequence gives primes for which k(p) exceeds k(q) for all primes q < p.

2, 7, 17, 19, 59, 167, 197, 227, 317, 457, 521, 1637, 1861, 1997, 2053, 3833, 5227, 19891, 47303, 54973, 58603, 124567, 138163, 170167, 707467, 1637429, 1940777, 3717731, 4722079, 17886697, 27507569, 73342163, 154205101, 160561133, 186668543, 429364379, 458121431, 1459411661, 2140833967, 4028983027, 5189517859, 6184586189, 10352323829, 36673176307

Offset

1,1

Links

Table of n, a(n) for n=1..44.

Example

a(1)=2 because k(2)=1 (2*1*2+1=5 is prime);
a(2)=7 because k(7)=2 (2*1*7+1=15 is not prime, 2*2*7+1=29 is prime).

Crossrefs

Cf. A117673.

Sequence in context: A101568 A291528 A182575 * A227144 A105911 A038873

Adjacent sequences: A074881 A074882 A074883 * A074885 A074886 A074887

Keyword

nonn

Author

Mike Oakes, Oct 01 2002

Extensions

a(30)-a(38) from Don Reble, Jan 07 2013

a(39)-a(44) from Marco Frigerio, Mar 25 2019

Status

approved