A130176 Numbers n with property that the largest prime factor is a Sophie Germain prime.

2, 3, 4, 5, 6, 8, 9, 10, 11, 12, 15, 16, 18, 20, 22, 23, 24, 25, 27, 29, 30, 32, 33, 36, 40, 41, 44, 45, 46, 48, 50, 53, 54, 55, 58, 60, 64, 66, 69, 72, 75, 77, 80, 81, 82, 83, 87, 88, 89, 90, 92, 96, 99, 100, 106, 108, 110, 113, 115, 116, 120, 121, 123, 125, 128, 131, 132

Offset

1,1

Comments

Prime terms 2,3,5,11,23,29,... are in A005384.

A156541 is a subsequence. [Reinhard Zumkeller, Feb 10 2009]

A156660(A006530(a(n))) = 1. [Reinhard Zumkeller, Dec 03 2009]

Links

Table of n, a(n) for n=1..67.

Mathematica

Select[Range[2, 132], PrimeQ[FactorInteger[#][[-1, 1]]*2 + 1] &] (* Ivan Neretin, Aug 30 2015 *)

Crossrefs

Cf. A005384.

Sequence in context: A302540 A332487 A067942 * A156541 A325663 A277620

Adjacent sequences: A130173 A130174 A130175 * A130177 A130178 A130179

Keyword

nonn

Author

Zak Seidov, May 14 2007

Status

approved