A090082 Even pseudoprimes to base 5.

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)

Index entries for sequences related to pseudoprimes.

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

Adjacent sequences: A090079 A090080 A090081 * A090083 A090084 A090085

Keyword

nonn

Author

Labos Elemer, Nov 25 2003

Extensions

More terms from Farideh Firoozbakht, Sep 13 2006

Status

approved