A372881 - OEIS

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A372881

a(n) = Sum_{j=1..n} Sum_{k=1..n} gcd(j*k,n).

2

1, 7, 19, 44, 61, 133, 127, 256, 297, 427, 331, 836, 469, 889, 1159, 1408, 817, 2079, 1027, 2684, 2413, 2317, 1519, 4864, 2825, 3283, 4131, 5588, 2437, 8113, 2791, 7424, 6289, 5719, 7747, 13068, 3997, 7189, 8911, 15616, 4921, 16891, 5419, 14564, 18117, 10633, 6487, 26752

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

OFFSET

1,2

LINKS

Seiichi Manyama, Table of n, a(n) for n = 1..1000

PROG

(PARI) a(n) = sum(j=1, n, sum(k=1, n, gcd(j*k, n)));

CROSSREFS

Cf. A018804, A078430.

Sequence in context: A330854 A268926 A212955 * A155415 A155273 A277613

Adjacent sequences: A372878 A372879 A372880 * A372882 A372883 A372884

KEYWORD

nonn,mult

AUTHOR

Seiichi Manyama, May 15 2024

STATUS

approved