A091880 A049232 indexed by A000040.

1, 4, 9, 14, 15, 18, 21, 22, 25, 36, 39, 40, 48, 53, 59, 65, 67, 70, 72, 73, 74, 82, 85, 88, 99, 101, 110, 114, 122, 125, 127, 129, 130, 137, 143, 146, 147, 155, 158, 168, 174, 177, 180, 181, 188, 194, 198, 200, 202, 204, 213, 216, 219, 220, 224, 226, 229, 235

Offset

1,2

Comments

The asymptotic density of this sequence is 1 - 2 * Product_{p prime} (1-1/(p*(p-1))) = 1 - 2 * A005596 = 0.252088... - Amiram Eldar, Feb 28 2021

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Formula

a(n) = k such that A000040(k) = A049232(n).

Mathematica

Select[Range[100], ! SquareFreeQ[Prime[ # ] + 2] &] (* Zak Seidov, Oct 28 2008 *)

Crossrefs

Cf. A000040, A005596, A049232.

Sequence in context: A140343 A279230 A244037 * A141560 A071864 A312987

Adjacent sequences: A091877 A091878 A091879 * A091881 A091882 A091883

Keyword

easy,nonn

Author

Ray Chandler, Feb 15 2004

Status

approved