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A130437
Even pseudoprimes to base 19.
13
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
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.
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.
Sequence in context: A052682 A214592 A372522 * A119813 A370716 A119986
KEYWORD
nonn
AUTHOR
Alexander Adamchuk, May 26 2007
EXTENSIONS
More terms from Robert G. Wilson v, Jun 01 2007
STATUS
approved