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A085999 For p = prime(n), a(n) is the smallest base-2 pseudoprime N (that is, 2^(N-1) = 1 mod N) such that p divides N. 2
561, 645, 1729, 341, 1105, 561, 1387, 2047, 2465, 341, 2701, 6601, 645, 4371, 8321, 13747, 29341, 8911, 19951, 1387, 30889, 88561, 2047, 18721, 60701, 31621, 680627, 4033, 3277, 1905, 357761, 74665, 1419607, 88357, 4681, 8321, 422659, 83333 (list; graph; refs; listen; history; internal format)
OFFSET

2,1

COMMENTS

Tables compiled by Pinch were used. Sequence A086000 lists a(n) / prime(n).

LINKS

R. G. E. Pinch, Pseudoprimes and their factors (FTP)

Eric Weisstein's World of Mathematics, Pseudoprime

EXAMPLE

a(11) = 341 because prime(11) = 31 and 341 is the first pseudoprime divisible by 31.

MATHEMATICA

Table[p=Prime[n]; m=MultiplicativeOrder[4, p]; k=1; While[psp=p(1+2*m*k); PowerMod[2, psp-1, psp]!=1, k++ ]; psp, {n, 2, 100}]

CROSSREFS

Cf. A001567 (base-2 pseudoprimes), A086000.

Sequence in context: A192297 A080747 A074380 * A137198 A194231 A141705

Adjacent sequences:  A085996 A085997 A085998 * A086000 A086001 A086002

KEYWORD

easy,nonn

AUTHOR

T. D. Noe (noe(AT)sspectra.com), Jul 08 2003

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Last modified February 15 08:15 EST 2012. Contains 205725 sequences.