id:A051678 - OEIS Search Results

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Square-pyramid-tree numbers: a(n)=sum(b(m),m=1..n), b(m)=1^2, 1^2,2^2, 1^2,2^2,3^2,..=(A002260)^2.

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1, 2, 6, 7, 11, 20, 21, 25, 34, 50, 51, 55, 64, 80, 105, 106, 110, 119, 135, 160, 196, 197, 201, 210, 226, 251, 287, 336, 337, 341, 350, 366, 391, 427, 476, 540, 541, 545, 554, 570, 595, 631, 680, 744, 825, 826, 830, 839, 855, 880, 916, 965, 1029, 1110, 1210 (list; graph; listen)

	OFFSET	`1,2`
	FORMULA	`a(n * (n + 1)/2 + m) = 1/12 * n * (n + 2) * (n + 1)^2 + 1/6 * m * (m + 1) * (2 * m + 1) = A002415(n) + A000330(m), m = 0...n + 1, n = 1, 2, 3..`
	CROSSREFS	`A002260, A000330, A002415.` `Sequence in context: A032926 A088227 A145489 this_sequence A079906 A072147 A124319` `Adjacent sequences: A051675 A051676 A051677 this_sequence A051679 A051680 A051681`
	KEYWORD	`easy,nice,nonn`
	AUTHOR	`Klaus Strassburger (strass(AT)ddfi.uni-duesseldorf.de)`

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Last modified December 15 00:47 EST 2009. Contains 170825 sequences.

AT&T Labs Research