A112666 Semiprimes n such that 3*n + 4 is a square.

4, 15, 39, 55, 95, 119, 319, 407, 559, 799, 1007, 1159, 1679, 2407, 2759, 3007, 3959, 5207, 6439, 8639, 10207, 10679, 10919, 13199, 16279, 18407, 19039, 23407, 24119, 31007, 32239, 33919, 36079, 50959, 52007, 58519, 66007, 67799, 69007, 73319

Offset

1,1

Links

Table of n, a(n) for n=1..40.

Mathematica

fQ[n_] := Plus @@ Last /@ FactorInteger@n == 2 && IntegerQ@Sqrt[3n + 4]; Select[ Range@100000, fQ[ # ] &] (* Robert G. Wilson v *)
Select[Range[75000], PrimeOmega[#]==2&&IntegerQ[Sqrt[3#+4]]&] (* Harvey P. Dale, Sep 22 2011 *)

Crossrefs

Sequence in context: A296268 A209409 A241302 * A014629 A062486 A193226

Adjacent sequences: A112663 A112664 A112665 * A112667 A112668 A112669

Keyword

nonn

Author

Giovanni Teofilatto, Dec 29 2005

Extensions

More terms from Robert G. Wilson v, Dec 30 2005

Status

approved