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A090083 Even pseudoprimes to base 9. 14
4, 8, 28, 52, 286, 364, 532, 616, 946, 1036, 1288, 2806, 2926, 3052, 4376, 4636, 5356, 6364, 8744, 8866, 11476, 12124, 15964, 17446, 19096, 19684, 21196, 21736, 24046, 24388, 26596, 31876 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..1000

Index entries for sequences related to pseudoprimes

MATHEMATICA

Do[s=Mod[ -1+9^(n-1), n]; If[Equal[s, 0]&&!PrimeQ[n]&&EvenQ[n], Print[n]], {n, 1, 1000000}]

PROG

(PARI) is(n)=Mod(9, 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(9, n)^(n-1)==1, print1(n", "))); p=q) \\ Charles R Greathouse IV, Apr 12 2012

CROSSREFS

Cf. A020138.

Sequence in context: A117864 A020138 A306448 * A034515 A189546 A059480

Adjacent sequences:  A090080 A090081 A090082 * A090084 A090085 A090086

KEYWORD

nonn

AUTHOR

Labos Elemer, Nov 25 2003

STATUS

approved

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Last modified October 26 09:03 EDT 2020. Contains 338027 sequences. (Running on oeis4.)