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A176100 Even numbers that are not semiprimes, or, twice the nonprimes. 4
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified March 3 03:03 EST 2021. Contains 341756 sequences. (Running on oeis4.)