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

1,3

Links

Table of n, a(n) for n=1..52.

Formula

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

Prog

(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

Crossrefs

Cf. A126080, A128487.

Sequence in context: A222136 A339652 A279787 * A359366 A226303 A117781

Adjacent sequences: A128485 A128486 A128487 * A128489 A128490 A128491

Keyword

nonn

Author

Leroy Quet, Mar 04 2007

Extensions

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

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

Status

approved