A130437 - OEIS

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A130437

Even pseudoprimes to base 19.

6, 18, 906, 5466, 257302, 825366, 1880082, 6637546, 6765826, 8936722, 9483706, 34087054, 51914026, 54806454, 57663334, 57819882, 67372378, 91835206, 98963734, 102985926, 117697186, 134457346, 143888806, 172530646, 206623266

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..145 (terms below 10^11; terms 1..51 from Robert G. Wilson v)

Eric Weisstein's World of Mathematics, Fermat Pseudoprime.

Index entries for sequences related to pseudoprimes.

MATHEMATICA

lst = {}; Do[ If[ PowerMod[19, 2n - 1, 2n] == 1, AppendTo[lst, 2n]], {n, 2, 2*10^9}]; lst (* Robert G. Wilson v, Jun 01 2007 *)

PROG

(PARI) is(k) = k > 2 && !(k % 2) && Mod(19, k)^(k-1) == 1; \\ Amiram Eldar, Sep 29 2024

CROSSREFS

Cf. A020147 = Pseudoprimes to base 19. 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, A130438, A130439, A130440, A130441, A130442, A130443.

Cf. A020147, A006935, A130433, A090082, A090083, A090084, A090085, A130434, A130435, A130436, A130438, A130439, A130440, A130441, A130442, A130443.

Sequence in context: A052682 A214592 A372522 * A119813 A370716 A119986

Adjacent sequences: A130434 A130435 A130436 * A130438 A130439 A130440

KEYWORD

nonn

AUTHOR

Alexander Adamchuk, May 26 2007

EXTENSIONS

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

STATUS

approved