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A269788
Primes p such that 2*p + 47 is a square.
1
17, 37, 61, 89, 157, 197, 241, 397, 457, 521, 661, 1277, 1381, 1489, 1601, 2089, 2221, 2357, 2789, 3257, 3761, 4877, 5077, 5281, 5701, 6361, 7057, 7297, 7541, 7789, 8297, 8821, 10781, 11681, 12301, 13921, 15289, 15641, 17837, 18217, 19381, 19777, 20177, 21401
OFFSET
1,1
COMMENTS
Primes of the form 2*k^2 + 2*k - 23.
FORMULA
a(1) = 17 because 2*17 + 47 = 81, which is a square.
MATHEMATICA
Select[Prime[Range[2500]], IntegerQ[Sqrt[2 # + 47]] &]
PROG
(Magma) [p: p in PrimesUpTo(50000) | IsSquare(2*p+47)];
(PARI) lista(nn) = {forprime(p=2, nn, if(issquare(2*p + 47), print1(p, ", "))); } \\ Altug Alkan, Mar 24 2016
CROSSREFS
Cf. A000040.
Subsequence of A002144, A045371.
Cf. similar sequences listed in A269784.
Sequence in context: A225077 A146328 A161549 * A146348 A050952 A256517
KEYWORD
nonn
AUTHOR
Vincenzo Librandi, Mar 24 2016
STATUS
approved