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A089681 Numbers n such that 3n^2 - 1 is prime. 2
1, 2, 4, 6, 8, 12, 14, 18, 22, 26, 28, 30, 34, 40, 44, 48, 50, 52, 54, 58, 60, 70, 72, 74, 76, 78, 92, 96, 110, 118, 122, 136, 138, 144, 150, 154, 158, 164, 176, 182, 186, 188, 204, 210, 214, 216, 230, 232, 234, 236, 242, 248, 260, 268, 272, 274, 280, 298, 304, 308 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

REFERENCES

M. Cerasoli, F. Eugeni and M. Protasi, Elementi di Matematica Discreta, Bologna 1988

Emanuele Munarini and Norma Zagaglia Salvi, Matematica Discreta,UTET, CittaStudiEdizioni, Milano 1997

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

MATHEMATICA

Select[Range[500], PrimeQ[3#^2-1]&] (* Harvey P. Dale, Oct 09 2011 *)

PROG

(PARI) is(n)=isprime(3*n^2-1) \\ Charles R Greathouse IV, Jun 05 2017

CROSSREFS

Sequence in context: A260652 A324102 A089623 * A227308 A214294 A233578

Adjacent sequences:  A089678 A089679 A089680 * A089682 A089683 A089684

KEYWORD

easy,nonn

AUTHOR

Giovanni Teofilatto, Jan 05 2004

EXTENSIONS

More terms from Rick L. Shepherd, May 18 2005

STATUS

approved

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Last modified April 20 02:06 EDT 2019. Contains 322291 sequences. (Running on oeis4.)