A197640 Numbers not representable as the sum of two coprime, squarefree, composite, positive integers.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 30, 32, 33, 34, 35, 36, 38, 39, 40, 42, 44, 45, 46, 48, 50, 51, 52, 54, 56, 58, 60, 62, 63, 64, 66, 70, 72, 75, 78, 80, 82, 84, 88, 90, 96, 100, 102, 105, 108, 110, 114, 120, 126, 130, 132, 138, 140, 144, 150, 156, 168, 180, 190, 204, 210, 240, 270, 330, 420

Offset: 1

Author

Jason Holland, Oct 16 2011

Keywords

• nonn

Comments

a(87) = 420 is probably the last term.

Crossrefs

Cf. A197629, A096076.

Programs

PARI

is(n)=for(k=6,n\2,if(gcd(k,n-k)==1&&!isprime(k)&&!isprime(n-k)&&issquarefree(k)&&issquarefree(n-k),return(0)));1 \\ Charles R Greathouse IV, Oct 18 2011