1,2

Table of n, a(n) for n=1..57.

a(n) ~ 3n. - Charles R Greathouse IV, May 25 2011

(MAGMA) A172182:=func<n | exists{k: k in [0..n div 6] | n in [6*k+1, 6*k+2] and not IsPrime(n)}>; [ n: n in [1..247] | A172182(n) ]; // Bruno Berselli, May 25 2011

Cf. A045375.

Sequence in context: A309355 A063288 A136798 * A091575 A091572 A096786

Adjacent sequences: A172179 A172180 A172181 * A172183 A172184 A172185

nonn,easy

Juri-Stepan Gerasimov, Jan 28 2010

Entries checked by R. J. Mathar, May 22 2010

Retitled by Charles R Greathouse IV, May 25 2011

approved