A086983 Primes of the form 2^r*p^s - 1, where p is an odd prime.

2, 3, 5, 7, 11, 13, 17, 19, 23, 31, 37, 43, 47, 53, 61, 67, 71, 73, 79, 97, 103, 107, 127, 151, 157, 163, 191, 193, 199, 211, 223, 241, 271, 277, 283, 313, 331, 337, 367, 383, 397, 421, 431, 457, 463, 487, 499, 523, 541, 547, 577, 607, 613, 631, 647, 661, 673

Offset: 1

Author

Ray Chandler, Aug 02 2003

Keywords

• nonn

Comments

Primes p such that p+1 has at most one odd prime divisor.

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A005105, A077497, A077498, A077499, A077500.

Cf. also A005109, A077313, A077314, A077315.

Programs

Maple

N:= 1000: # to get all terms <= N
Primes:= select(isprime, [$3..(N+1)/2]):
sort(convert(select(isprime, {2,seq(seq(seq(2^r*p^s-1, r = 1 .. ilog2((N+1)/p^s)),s=0..floor(log[p]((N+1)/2))),p=Primes)}),list)); # Robert Israel, Jun 13 2018