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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
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
Sequence in context: A222136 A339652 A279787 * A359366 A226303 A117781
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 July 17 16:16 EDT 2024. Contains 374377 sequences. (Running on oeis4.)