A049630 a(n) = Sum_{i=0..floor(n/2)} T(2i,n-2i) where T is A049627.

1, 2, 4, 7, 10, 17, 22, 34, 42, 61, 72, 100, 116, 154, 176, 224, 250, 314, 348, 427, 470, 563, 612, 726, 786, 918, 988, 1141, 1220, 1399, 1492, 1694, 1802, 2030, 2148, 2404, 2534, 2820, 2968, 3284, 3444, 3796, 3976, 4361, 4562, 4979, 5192, 5654, 5890, 6389

Offset

0,2

Links

Table of n, a(n) for n=0..49.

Prog

(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, n-2*i)); \\ Michel Marcus, Aug 06 2021

Crossrefs

Cf. A049627.

Sequence in context: A365068 A131752 A062365 * A032705 A332639 A281168

Adjacent sequences: A049627 A049628 A049629 * A049631 A049632 A049633

Keyword

nonn

Author

Clark Kimberling

Extensions

More terms from Sean A. Irvine, Aug 05 2021

Status

approved