A049632 a(n) = T(n,n), array T as in A049627.

1, 4, 6, 10, 14, 22, 26, 38, 46, 58, 66, 86, 94, 118, 130, 146, 162, 194, 206, 242, 258, 282, 302, 346, 362, 402, 426, 462, 486, 542, 558, 618, 650, 690, 722, 770, 794, 866, 902, 950, 982, 1062, 1086, 1170, 1210, 1258, 1302, 1394, 1426, 1510, 1550, 1614, 1662

Offset: 0

Author

Clark Kimberling

Keywords

• nonn

Crossrefs

Cf. A049627, A049643, A005728.

Programs

PARI

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

Formula

a(n) = 2*A005728(n) if n>=1. - R. J. Mathar, Feb 05 2008

Extensions

More terms from Sean A. Irvine, Aug 05 2021