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A090697
Numbers n such that n^2/2 - 1 is a prime.
5
4, 6, 8, 12, 14, 16, 20, 22, 26, 30, 34, 36, 42, 44, 48, 50, 56, 68, 72, 76, 78, 82, 84, 86, 90, 92, 98, 100, 104, 112, 118, 124, 126, 128, 138, 146, 152, 160, 162, 170, 174, 182, 184, 190, 196, 204, 216, 218, 224, 226, 230, 236, 250, 252, 254, 264, 268, 274, 280
OFFSET
1,1
COMMENTS
A066436 gives resulting primes p such that 2p+2 is square. - Ray Chandler, Dec 25 2003
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
FORMULA
a(n) = 2*A066049(n) = A110558(n)/2. - Ray Chandler, Dec 25 2003
MATHEMATICA
Select[Range[2, 300, 2], PrimeQ[#^2/2-1]&] (* Harvey P. Dale, Apr 05 2014 *)
PROG
(PARI) isok(n) = !(n % 2) && isprime(n^2/2 - 1); \\ Michel Marcus, Jul 23 2016
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Giovanni Teofilatto, Dec 20 2003
EXTENSIONS
Corrected and extended by Ray Chandler, Dec 25 2003
STATUS
approved