A130435 Even pseudoprimes to base 13.

4, 6, 12, 244, 276, 2806, 5028, 10308, 40132, 51118, 115644, 185646, 216492, 237084, 789636, 936046, 941818, 1062876, 1237276, 1469716, 2119002, 2201002, 2410354, 2446426, 3198196, 4319052, 4979316, 5329468, 5496492, 7171876, 9513076

Offset: 1

Author

Alexander Adamchuk, May 26 2007

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..300 (terms 1..101 from Robert G. Wilson v)
• Eric Weisstein's World of Mathematics, Fermat Pseudoprime.
• Index entries for sequences related to pseudoprimes.

Crossrefs

Cf. A020141, A006935, A130433, A090082, A090083, A090084, A090085, A130434, A130436, A130437, A130438, A130439, A130440, A130441, A130442, A130443.

Programs

Mathematica

Do[ f=PowerMod[ 13, 2n-1, 2n ]; If[ f==1, Print[ 2n ] ], {n,2,1000000} ] (* Robert G. Wilson v, May 31 2007 *)

PARI

is(k) = k > 2 && !(k % 2) &&  Mod(13, k)^(k-1) == 1; \\ Amiram Eldar, Sep 18 2024

Extensions

a(26)-a(31) from Robert G. Wilson v, May 31 2007