A173281 Let a(1) = 1. Given a(1), ..., a(2^t), find the least k such that a(1) + 2^k, a(2) + 2^k, ..., a(2^t) + 2^k are all composite and a(1) + 2^k > a(2^t). Then a(2^t+i) = a(i) + 2^k for all 1 <= i <= 2^t.

1, 9, 2049, 2057, 4097, 4105, 6145, 6153, 524289, 524297, 526337, 526345, 528385, 528393, 530433, 530441, 16777217, 16777225, 16779265, 16779273, 16781313, 16781321, 16783361, 16783369, 17301505, 17301513, 17303553, 17303561, 17305601, 17305609, 17307649, 17307657

Offset

1,2

Comments

This sequence can be represented by a single clause in a CNF IsPrime() function.

Links

Table of n, a(n) for n=1..32.

Prog

(PARI) step(v)=my(k=log(v[#v])\log(2)); while(1, for(i=1, #v, k++; if(ispseudoprime(2^k+v[i]), next(2))); return(concat(v, vector(#v, i, 2^k+v[i])))) \\ Charles R Greathouse IV, Oct 25 2012

Crossrefs

Sequence in context: A162140 A006945 A089825 * A004820 A320982 A316396

Adjacent sequences: A173278 A173279 A173280 * A173282 A173283 A173284

Keyword

nonn

Author

Russell Easterly, Feb 14 2010

Extensions

a(9)-a(32) from Charles R Greathouse IV, Oct 25 2012

Status

approved