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A069497 Triangular numbers of the form 6k. 1
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)= 3*a(n-1) -5*a(n-2) +7*a(n-3) -7*a(n-4) +5*a(n-5) -3*a(n-6) +a(n-7). G.f.: 6*x*(x^2-x+1)*(x^2+4*x+1)/((1+x^2)^2*(1-x)^3). (apparently 6*A154293). [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, 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 September 1 04:07 EDT 2014. Contains 246282 sequences.