A111147 Numbers n such that 5*n^2 + 1 is prime.

6, 18, 36, 42, 84, 102, 108, 132, 144, 150, 162, 168, 174, 186, 192, 246, 276, 288, 300, 312, 330, 354, 372, 384, 396, 402, 456, 462, 498, 510, 522, 528, 552, 564, 570, 582, 612, 636, 648, 708, 738, 804, 816, 834, 840, 846, 882, 888, 924, 930, 942, 972, 990

Offset

1,1

Links

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

Example

If n=312 then 5*n^2 + 1 = 486721 (prime).

Mathematica

Select[Range[1000], PrimeQ[5*#^2 + 1] &] (* Stefan Steinerberger, Feb 26 2006 *)

Prog

(PARI) is(n)=isprime(5*n^2+1) \\ Charles R Greathouse IV, Jun 12 2017

Crossrefs

Sequence in context: A271123 A271303 A110965 * A333821 A358843 A328586

Adjacent sequences: A111144 A111145 A111146 * A111148 A111149 A111150

Keyword

nonn,easy

Author

Parthasarathy Nambi, Oct 18 2005

Extensions

More terms from Stefan Steinerberger, Feb 26 2006

Status

approved