id:A140236 - OEIS Search Results

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Double tetrahedral (or pyramidal) numbers: a(n)= k(k+1)(k+2)/6 where k= n(n+1)(n+2)/6.

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0, 1, 20, 220, 1540, 7770, 30856, 102340, 295240, 762355, 1798940, 3939936, 8104460, 15803060, 29426320, 52636760, 90889616, 152112005, 247574180, 392991060, 609896980, 927341646, 1383960600, 2030479100, 2932714200 (list; graph; listen)

	OFFSET	`1,3`
	FORMULA	`a(n) = (n (1 + n) (2 + n) (3 + n) (2 + n^2) (12 + n (1 + n) (2 + n)))/1296`
	MATHEMATICA	`Table[(n (1 + n) (2 + n) (3 + n) (2 + n^2) (12 + n (1 + n) (2 + n)))/1296, {n, 0, 20}]`
	CROSSREFS	`Cf. A000292.` `Sequence in context: A128823 A141790 A125408 this_sequence A004411 A140354 A155673` `Adjacent sequences: A140233 A140234 A140235 this_sequence A140237 A140238 A140239`
	KEYWORD	`nonn`
	AUTHOR	`Artur Jasinski (grafix(AT)csl.pl), May 14 2008`

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Last modified December 4 15:11 EST 2009. Contains 170347 sequences.

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