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A090082
Even pseudoprimes to base 5.
16
4, 124, 5662, 11476, 59356, 80476, 91636, 250876, 261964, 482516, 1385836, 1892458, 1926676, 2428084, 2589796, 3743476, 4101796, 6797764, 9155476, 10701076, 10743436, 11263396, 13799836, 13859956, 15570556, 20396476
OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..910 (terms below 10^12, calculated from the b-file at A005936; terms 1..100 from Charles R Greathouse IV)
MATHEMATICA
Do[s=Mod[ -1+5^(n-1), n]; If[Equal[s, 0]&&!PrimeQ[n]&&EvenQ[n], Print[n]], {n, 1, 1000000}]
PROG
(PARI) is(n)=Mod(5, n)^(n-1)==1&&!isprime(n)&&n%2==0 \\ Charles R Greathouse IV, Apr 12 2012
(PARI) p=2; forprime(q=3, 1e8, forstep(n=p+1, q-1, 2, if(Mod(5, n)^(n-1)==1, print1(n", "))); p=q) \\ Charles R Greathouse IV, Apr 12 2012
CROSSREFS
Cf. A005936.
Sequence in context: A241648 A197779 A197610 * A243010 A343427 A209040
KEYWORD
nonn
AUTHOR
Labos Elemer, Nov 25 2003
EXTENSIONS
More terms from Farideh Firoozbakht, Sep 13 2006
STATUS
approved