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A128488 a(n) = sum of terms in n-th row of irregular table A128487. 2
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: A023896 A222136 A279787 * A226303 A117781 A075100

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

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Last modified October 22 14:44 EDT 2019. Contains 328318 sequences. (Running on oeis4.)