id:A081860 - OEIS Search Results

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a(n)=sum(k=0,n-1, sigma(2k+1)*sigma_3(n-k)).

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1, 13, 70, 247, 671, 1547, 3178, 5916, 10317, 17088, 26818, 40703, 60034, 85463, 119288, 163736, 218924, 288933, 377482, 482734, 612535, 772291, 955604, 1177050, 1443522, 1742481, 2097702, 2517368, 2978851, 3519151, 4152486, 4836104 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`An amazing Ramanujan identity. Here sigma_m(n) denotes sum( d dividing n, d^m)`
	REFERENCES	`Bruce Berndt, Ramanujan's Notebooks Part II, Springer-Verlag; page 301.`
	FORMULA	`a(n) = 1/240*(sigma_5(2n+1)-sigma(2n+1))`
	CROSSREFS	`Cf. A000203, A001158, A001160.` `Sequence in context: A055880 A105058 A085461 this_sequence A050403 A031442 A066831` `Adjacent sequences: A081857 A081858 A081859 this_sequence A081861 A081862 A081863`
	KEYWORD	`nonn`
	AUTHOR	`Benoit Cloitre (benoit7848c(AT)orange.fr), Apr 11 2003`

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Last modified July 26 13:41 EDT 2008. Contains 142293 sequences.

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