A195328 Number of bases to which terms of A141768 are strong pseudoprimes.

2, 4, 6, 18, 50, 54, 162, 242, 450, 486, 882, 1058, 1782, 3042, 3078, 4050, 5202, 9522, 19602, 22050, 36450, 46818, 54450, 66978, 71442, 95922, 124002, 149058, 183618, 190962, 238050, 240570, 263538, 277830, 328050, 466578, 684450, 816642, 977202

Offset: 1

Author

Charles R Greathouse IV, Sep 15 2011

Keywords

• nonn

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..5476
• Index entries for sequences related to pseudoprimes

Crossrefs

Cf. A141768, A195327.

Programs

PARI

star(n)={n--; n>>valuation(n, 2)};
bases(n)=my(f=factor(n)[, 1], nu=valuation(f[1]-1, 2), nn = star(n)); for(i=2, #f, nu = min(nu, valuation(f[i] - 1, 2)); ); (1 + (2^(#f * nu) - 1) / (2^#f - 1)) * prod(i=1, #f, gcd(nn, star(f[i]))); \\ Given a value of A141768, this function transforms it to a term of this sequence.