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A143831
Numbers n such that 12n^2 - 1 is prime.
4
1, 2, 3, 4, 6, 7, 9, 11, 13, 14, 15, 17, 20, 22, 24, 25, 26, 27, 29, 30, 35, 36, 37, 38, 39, 46, 48, 55, 59, 61, 68, 69, 72, 75, 77, 79, 82, 88, 91, 93, 94, 102, 105, 107, 108, 115, 116, 117, 118, 121, 124, 130, 134, 136, 137, 140, 149, 152, 154, 157, 158, 159, 162, 167
OFFSET
1,2
MATHEMATICA
p = 12; a = {}; Do[k = p x^2 - 1; If[PrimeQ[k], AppendTo[a, x]], {x, 1, 1000}]; a
PROG
(PARI) is(n)=isprime(12*n^2-1) \\ Charles R Greathouse IV, Feb 20 2017
KEYWORD
nonn
AUTHOR
Artur Jasinski, Sep 02 2008
STATUS
approved