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A078430 Sum of gcd(k^2,n) for 1 <= k <= n. +0
2
1, 3, 5, 10, 9, 15, 13, 28, 33, 27, 21, 50, 25, 39, 45, 88, 33, 99, 37, 90, 65, 63, 45, 140, 145, 75, 153, 130, 57, 135, 61, 240, 105, 99, 117, 330, 73, 111, 125, 252, 81, 195, 85, 210, 297, 135, 93, 440, 385, 435, 165, 250, 105, 459, 189, 364, 185, 171, 117, 450, 121 (list; graph; listen)
OFFSET

1,2

COMMENT

a(n) is the number of non-congruent solutions to x^2*y = 0 mod n. - Yuval Dekel (dekelyuval(AT)hotmail.com), Oct 17 2003

FORMULA

a(n) is multiplicative. G.f. for a(p^n), p a prime, is given by (1+(p-1)*x-p^2*x^2)/(1-p*x)/(1-p^3*x^2).

CROSSREFS

Cf. A018804, A069097, A069193.

Sequence in context: A121622 A083519 A069193 this_sequence A113858 A101130 A102309

Adjacent sequences: A078427 A078428 A078429 this_sequence A078431 A078432 A078433

KEYWORD

mult,nonn

AUTHOR

Vladeta Jovovic (vladeta(AT)eunet.rs), Dec 30 2002

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Last modified November 23 17:09 EST 2009. Contains 167438 sequences.


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