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

Author

Vladimir Joseph Stephan Orlovsky, Apr 23 2010

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Cf. A097698, A108701

Programs

Mathematica

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