A128488 a(n) = sum of terms in n-th row of irregular table A128487.

0, 1, 3, 4, 10, 9, 21, 16, 27, 25, 55, 36, 78, 49, 45, 64, 136, 81, 171, 100, 84, 121, 253, 144, 250, 169, 243, 196, 406, 105, 465, 256, 198, 289, 175, 324, 666, 361, 273, 400, 820, 189, 903, 484, 405, 529, 1081, 576, 1029, 625, 459, 676

Offset: 1

Author

Leroy Quet, Mar 04 2007

Keywords

• nonn

Crossrefs

Cf. A126080, A128487.

Programs

PARI

as(n) = my(f=factor(n)); vecsum(Vec(select(x->(x==1), vector(n-1, j, sum(k=1, #f~, gcd(j, f[k,1]) == 1)), 1))); \\ Michel Marcus, Oct 25 2017

Formula

a(n) = n *A126080(n)/2, for all n >= 1.

Extensions

More terms from R. J. Mathar, Oct 08 2007

a(1)=0 prepended by Michel Marcus, Oct 25 2017