A049631 a(n) = Sum_{i=0..floor(n/2)} T(2i+1,n-2i-1) where T is A049627.

0, 2, 4, 7, 12, 17, 26, 34, 50, 61, 84, 100, 132, 154, 198, 224, 280, 314, 384, 427, 514, 563, 666, 726, 848, 918, 1062, 1141, 1306, 1399, 1586, 1694, 1912, 2030, 2274, 2404, 2672, 2820, 3124, 3284, 3616, 3796, 4160, 4361, 4766, 4979, 5418, 5654, 6132, 6389

Offset: 0

Author

Clark Kimberling

Keywords

• nonn

Crossrefs

Cf. A049627.

Programs

PARI

T(n,k) = (n+1)*(k+1) - sum(i=0, n, sum(j=0, k, gcd(i,j)>1)); \\ A049627
a(n) = sum(i=0, n\2, T(2*i+1, n-2*i-1)); \\ Michel Marcus, Aug 06 2021

Extensions

More terms and name corrected by Sean A. Irvine, Aug 05 2021