A130442 Even pseudoprimes to base 41.

4, 8, 10, 20, 40, 344, 4870, 6892, 17230, 68920, 250820, 296440, 317032, 368722, 369370, 451426, 472312, 473240, 632270, 2326472, 3186730, 3429190, 4438760, 4670956, 4948456, 5509540, 8990356, 11817604, 11841436, 13094342, 17668360

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..366 (terms below 10^11; terms 1..146 from Robert G. Wilson v)

Eric Weisstein's World of Mathematics, Fermat Pseudoprime.

Index entries for sequences related to pseudoprimes.

Mathematica

Do[ f=PowerMod[ 41, 2n-1, 2n ]; If[ f==1, Print[ 2n ] ], {n, 2, 500000} ]
lst = {}; Do[ If[ PowerMod[41, 2n - 1, 2n] == 1, AppendTo[lst, 2n]], {n, 2, 2^31}]; lst (* Robert G. Wilson v, Jun 01 2007 *)

Prog

(PARI) is(k) = k > 2 && !(k % 2) &&  Mod(41, k)^(k-1) == 1; \\ Amiram Eldar, Sep 29 2024

Crossrefs

Cf. A020169 (pseudoprimes to base 41).

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

Cf. A130433 (even pseudoprimes to base 3).

Cf. A090082 (even pseudoprimes to base 5).

Cf. A090083, A090084, A090085.

Cf. A130434, A130435, A130436, A130437, A130438, A130439, A130440, A130441, A130443.

Cf. A020169, A006935, A130433, A090082, A090083, A090084, A090085, A130434, A130435, A130436, A130437, A130438, A130439, A130440, A130441, A130443.

Sequence in context: A048247 A276607 A338312 * A031073 A323151 A037004

Adjacent sequences: A130439 A130440 A130441 * A130443 A130444 A130445

Keyword

nonn

Author

Alexander Adamchuk, May 26 2007

Extensions

More terms from Robert G. Wilson v, Jun 01 2007

Status

approved