A128488 - OEIS

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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

(list; graph; refs; listen; history; text; internal format)

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