A108162 Least even pseudoprime > p to base p, where p = prime(n).

161038, 286, 124, 16806, 70, 244, 1228, 906, 154, 52, 66, 66, 344, 526974, 506, 286, 946, 130, 154, 370, 276, 2626, 1558, 19126, 176, 190, 946, 742, 186, 176, 3486, 190, 148, 246, 412, 10930, 186, 186, 3818, 14444, 1246, 316, 286, 276, 532, 426, 310, 246

Offset

1,1

Comments

Some numbers appear as a multiple terms in a(n). For example, a(n) = 946 for n = {17,27,64,66,73,75,97,113,114,117,128,139,143,152,153,155} for corresponding prime p = {59,103,311,317,367,379,509,617,619,643,719,797,823,881,883,907}. There are some twin terms such that a(n) = a(n+1). For example, a(11) = a(12) = 66, a(37) = a(38) = 186, a(113) = a(114) = 946, a(152) = a(153) = 946, a(227) = a(228) = 2626.

The indices of records are 1, 14, 354, 549, 1302, 2679, 3743, 3998, 4627, 6880, ... with record values of 161038, 526974, 1234806, 1893126, 1930546, 3347398, 3860962, 5073706, 6376126, 61161946, ... - Amiram Eldar, Sep 10 2019

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Eric Weisstein's World of Mathematics, Fermat Pseudoprime.

Index entries for sequences related to pseudoprimes

Mathematica

a[n_] := Module[{p = Prime[n]}, k = p+1; If[OddQ[k], k++]; While[GCD[p, k] != 1 || PowerMod[p, k, k] != p, k+=2]; k]; Array[a, 100] (* Amiram Eldar, Sep 10 2019 *)

Crossrefs

Cf. A006935 (Even pseudoprimes (or primes) to base 2: n divides 2^n - 2, n even).

Cf. A130433, A090082, A130434, A090084, A130435, A130436, A130437, A130438, A130439, A130440, A130441, A130442, A130443.

Sequence in context: A257186 A254986 A236977 * A270973 A287297 A296117

Adjacent sequences: A108159 A108160 A108161 * A108163 A108164 A108165

Keyword

nonn

Author

Alexander Adamchuk, May 26 2007

Status

approved