

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.


0



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
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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



