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A090082 Even pseudoprimes to base 5. 15
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..100

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

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Last modified July 5 15:05 EDT 2022. Contains 355099 sequences. (Running on oeis4.)