A226754 Numbers of the form p*q, p and q prime with q=2*p+3.

14, 65, 119, 377, 629, 779, 1769, 3827, 4559, 5777, 9179, 10877, 16109, 19109, 25877, 32639, 37949, 39059, 49769, 56279, 60377, 75077, 78209, 79799, 100127, 103739, 105569, 145529, 154289, 161027, 189419, 228149, 244649, 250277, 288419, 294527, 316409, 335789

Offset

1,1

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Mathematica

fa = FactorInteger; t[n_]:=Length[fa[n]] == 2 && fa[n][[1, 2]]== fa[n][[2, 2]] == 1 && 2 fa[n][[1, 1]]+3 == fa[n][[2, 1]]; Select[1+Range[200000], t]
Times@@#&/@Select[Table[{p, 2p+3}, {p, Prime[Range[200]]}], PrimeQ[#[[2]]]&] (* Harvey P. Dale, Jul 03 2021 *)

Prog

(PARI) list(lim)=my(v=List(), q); forprime(p=2, (sqrt(8*lim+9)-3)\4, if(isprime(q=2*p+3), listput(v, p*q))); Vec(v) \\ Charles R Greathouse IV, Nov 19 2013

Crossrefs

Cf. A129521, A156592, A226755.

Sequence in context: A126401 A275268 A304873 * A058092 A213757 A249290

Adjacent sequences: A226751 A226752 A226753 * A226755 A226756 A226757

Keyword

nonn

Author

José María Grau Ribas, Jun 16 2013

Status

approved