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Search: id:A051941
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| A051941 |
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Truncated triangular pyramid numbers: a(n)=sum(k*(k+1)/2-30,k=8..n). |
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+0
2
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| 6, 21, 46, 82, 130, 191, 266, 356, 462, 585, 726, 886, 1066, 1267, 1490, 1736, 2006, 2301, 2622, 2970, 3346, 3751, 4186, 4652, 5150, 5681, 6246, 6846, 7482, 8155, 8866, 9616, 10406, 11237, 12110, 13026, 13986, 14991, 16042, 17140, 18286, 19481
(list; graph; listen)
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OFFSET
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8,1
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FORMULA
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a(n)=1/6*(n-7)*(n^2+10*n-108)
Binomial transform of [6, 15, 10, 1, 0, 0, 0,...]. - Gary W. Adamson (qntmpkt(AT)yahoo.com), Oct 22 2007
O.g.f.: -x^8*(-6+3*x+2*x^2)/(-1+x)^4. a(n+1)-a(n) = A051940(n+1) . a(n) = 4*a(n-1) -6*a(n-2) +4*a(n-3) -a(n-4)- R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 17 2008
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CROSSREFS
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A000292.
Sequence in context: A119868 A081266 A087863 this_sequence A028345 A097124 A135454
Adjacent sequences: A051938 A051939 A051940 this_sequence A051942 A051943 A051944
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KEYWORD
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easy,nice,nonn
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AUTHOR
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Klaus Strassburger (strass(AT)ddfi.uni-duesseldorf.de), Dec 21 1999
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