A069497 - OEIS

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A069497

Triangular numbers of the form 6k.

0, 6, 36, 66, 78, 120, 210, 276, 300, 378, 528, 630, 666, 780, 990, 1128, 1176, 1326, 1596, 1770, 1830, 2016, 2346, 2556, 2628, 2850, 3240, 3486, 3570, 3828, 4278, 4560, 4656, 4950, 5460, 5778, 5886, 6216, 6786, 7140, 7260, 7626, 8256, 8646, 8778, 9180 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`0,2`
	LINKS	`Table of n, a(n) for n=0..45.`
	FORMULA	`a(n)=A000217(A112652(n+1)-1). - R. J. Mathar, Aug 21 2007` `a(n)= 3a(n-1) -5a(n-2) +7a(n-3) -7a(n-4) +5a(n-5) -3a(n-6) +a(n-7). G.f.: 6x(x^2-x+1)(x^2+4x+1)/((1+x^2)^2(1-x)^3). (apparently 6A154293). [From R. J. Mathar, Nov 18 2009]`
	MAPLE	`a[0] := 0:a[1] := 3:a[2] := 8:a[3] := 11:seq((12(floor(i/4))+a[i mod 4])(12*(floor(i/4))+a[i mod 4]+1)/2, i=1..100);`
	CROSSREFS	`Sequence in context: A226119 A036148 A134639 * A139249 A070150 A161144` `Adjacent sequences: A069494 A069495 A069496 * A069498 A069499 A069500`
	KEYWORD	`nonn`
	AUTHOR	`Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Mar 30 2002`
	EXTENSIONS	`More terms from Sascha Kurz, Apr 01 2002` `More terms from R. J. Mathar, Aug 21 2007`
	STATUS	`approved`

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Last modified June 18 17:38 EDT 2013. Contains 226355 sequences.