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 A195328 Number of bases to which members of A141768 are strong pseudoprimes. 4

%I

%S 2,4,6,18,50,54,162,242,450,486,882,1058,1782,3042,3078,4050,5202,

%T 9522,19602,22050,36450,46818,54450,66978,71442,95922,124002,149058,

%U 183618,190962,238050,240570,263538,277830,328050,466578,684450,816642,977202

%N Number of bases to which members of A141768 are strong pseudoprimes.

%H Charles R Greathouse IV, <a href="/A195328/b195328.txt">Table of n, a(n) for n = 1..5476</a>

%H <a href="/index/Ps#pseudoprimes">Index entries for sequences related to pseudoprimes</a>

%o (PARI) star(n)={n--; n>>valuation(n, 2)};

%o 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 member of this sequence.

%Y Cf. A141768, A195327.

%K nonn

%O 1,1

%A _Charles R Greathouse IV_, Sep 15 2011

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Last modified August 9 14:23 EDT 2020. Contains 336323 sequences. (Running on oeis4.)