A176681 Numbers k such that k^2 +-5 are primes.

6, 12, 36, 72, 78, 168, 198, 204, 342, 432, 456, 492, 534, 588, 594, 666, 726, 756, 786, 804, 996, 1014, 1212, 1218, 1248, 1254, 1266, 1314, 1344, 1476, 1512, 1554, 1806, 1812, 1902, 2088, 2298, 2322, 2364, 2616, 2634, 3066, 3072, 3162, 3432, 3444, 3852

Offset

1,1

Links

Daniel Starodubtsev, Table of n, a(n) for n = 1..10000

Example

12 is in the sequence, because 12^2 + 5 = 149 and 12^2 - 5 = 139 are primes.

Mathematica

Select[Range[8! ], PrimeQ[ #^2-5]&&PrimeQ[ #^2+5]&]

Crossrefs

Cf. A097698, A108701

Sequence in context: A096932 A212976 A352621 * A064476 A324483 A239171

Adjacent sequences: A176678 A176679 A176680 * A176682 A176683 A176684

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Apr 23 2010

Status

approved