A176100 Even numbers that are not semiprimes, or, twice the nonprimes.

0, 2, 8, 12, 16, 18, 20, 24, 28, 30, 32, 36, 40, 42, 44, 48, 50, 52, 54, 56, 60, 64, 66, 68, 70, 72, 76, 78, 80, 84, 88, 90, 92, 96, 98, 100, 102, 104, 108, 110, 112, 114, 116, 120, 124, 126, 128, 130, 132, 136, 138, 140, 144, 148, 150, 152, 154, 156, 160, 162, 164

Offset

1,2

Links

Table of n, a(n) for n=1..61.

Formula

a(n)= 2*A141468(n).

A005843 \ A100484.

a(n) = A139270(n-1). [R. J. Mathar, May 03 2010]

Mathematica

2 Prepend[Select[Range@ 82, ! PrimeQ@ # &], 0] (* Michael De Vlieger, Feb 20 2017 *)

Prog

(PARI) isok(n) = !(n%2) && !isprime(n/2); \\ Michel Marcus, Feb 20 2017

Crossrefs

Cf. A001358, A005843, A100484, A141468.

Sequence in context: A340969 A180634 A139270 * A285658 A284802 A067884

Adjacent sequences: A176097 A176098 A176099 * A176101 A176102 A176103

Keyword

nonn,easy

Author

Juri-Stepan Gerasimov, Apr 08 2010, Apr 11 2010

Extensions

Entries checked by R. J. Mathar, Apr 16 2010

Status

approved