id:A078430 - OEIS Search Results

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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^2x^2)/(1-px)/(1-p^3x^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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