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Search: id:A069497
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| A069497 |
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Triangular numbers of the form 6k. |
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+0
2
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| 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; listen)
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OFFSET
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0,2
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FORMULA
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a(n)=A000217(A112652(n+1)-1). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), 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 (mathar(AT)strw.leidenuniv.nl), Nov 18 2009]
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MAPLE
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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);
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CROSSREFS
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Sequence in context: A121026 A036148 A134639 this_sequence A139249 A070150 A161144
Adjacent sequences: A069494 A069495 A069496 this_sequence A069498 A069499 A069500
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KEYWORD
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nonn,new
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Mar 30 2002
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EXTENSIONS
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More terms from Sascha Kurz (sascha.kurz(AT)uni-bayreuth.de), Apr 01 2002
More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 21 2007
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