A232721 Numbers not representable as the sum of two coprime nonprime numbers.

1, 3, 4, 6, 8, 12, 14, 18, 20, 24, 30, 32, 38, 42, 48, 54, 60, 72, 80, 84, 90, 108, 110, 132, 138, 140, 150, 180

Offset

1,2

Comments

Numbers n such that A185279(n) = 0. 1 and 3 together with A141096.

Links

Table of n, a(n) for n=1..28.

Mathematica

t = Table[Length[Select[Range[n/2], ! PrimeQ[#] && ! PrimeQ[n - #] && GCD[#, n - #] == 1 &]], {n, 2000}]; Flatten[Position[t, 0]] (* T. D. Noe, Dec 05 2013 *)

Crossrefs

Cf. A062303, A018252, A141095, A141098.

Sequence in context: A008864 A299763 A214583 * A227956 A320592 A225531

Adjacent sequences: A232718 A232719 A232720 * A232722 A232723 A232724

Keyword

nonn,full,fini

Author

Irina Gerasimova, Nov 28 2013

Status

approved