id:A077539 - OEIS Search Results

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a(n) = Floor[ T(n+1)!*T(n-1)!/{(T(n)!)^2}, where T(n) = n(n+1)/2 = the n-th triangular number.

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6, 20, 42, 71, 108, 152, 204, 263, 330, 403, 485, 573, 669, 773, 884, 1002, 1128, 1261, 1401, 1549, 1704, 1866, 2036, 2214, 2398, 2591, 2790, 2997, 3211, 3433, 3662, 3898, 4142, 4394, 4652, 4918, 5192, 5472, 5761, 6056, 6359, 6669, 6987 (list; graph; listen)

	OFFSET	`1,1`
	COMMENT	`The ratio itself is an integer only for n = 1, 2 and 3.`
	EXAMPLE	`a(1) = 6 = (23)/1, a(2) = 20 = (456)/(23) etc.`
	CROSSREFS	`Sequence in context: A031052 A097811 A143711 this_sequence A002943 A068377 A009946` `Adjacent sequences: A077536 A077537 A077538 this_sequence A077540 A077541 A077542`
	KEYWORD	`nonn`
	AUTHOR	`Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Nov 09 2002`
	EXTENSIONS	`More terms from Mark Hudson (mrmarkhudson(AT)hotmail.com), Feb 11 2003`

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Last modified December 10 00:48 EST 2009. Contains 170565 sequences.

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