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Search: id:A083374
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| 0, 6, 36, 120, 300, 630, 1176, 2016, 3240, 4950, 7260, 10296, 14196, 19110, 25200, 32640, 41616, 52326, 64980, 79800, 97020, 116886, 139656, 165600, 195000, 228150, 265356, 306936, 353220, 404550, 461280, 523776, 592416, 667590, 749700, 839160
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Triangular numbers t_n as n runs through the squares.
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FORMULA
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a(n) = A047928(n)/2 = A002415(n+1)*6 = A006011(n+1)*2 = A008911(n+1)*3. - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), May 09 2007
a(n)=C(n^2,2),n>=1. - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jan 07 2008
a(n)= 5*a(n-1)-10*a(n-2)+10*a(n-3)-5*a(n-4)+a(n-5). G.f.: -6*x^2*(1+x)/(x-1)^5. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 10 2009]
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MAPLE
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a:=n->sum(sum(n^2/2, j=2..n), k=0..n): seq(a(n), n=1..36); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), May 09 2007
seq(binomial(n^2, 2), n=1..36); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jan 07 2008
a:=n->add(binomial(n, 2)+add(binomial(n, 2), j=1..n), j=1..n):seq(a(n), n=1..35); [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Aug 27 2008]
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MATHEMATICA
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Table[n^2*(n^2-1)/2, {n, 40}] - T. D. Noe (noe(AT)sspectra.com), Oct 25 2006
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CROSSREFS
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a(n) = (n + 1) * A006002(n).
Cf. A002415, A006011, A008911, A047928.
A008911 [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Aug 27 2008]
Sequence in context: A060521 A036141 A061804 this_sequence A061707 A056375 A018214
Adjacent sequences: A083371 A083372 A083373 this_sequence A083375 A083376 A083377
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KEYWORD
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easy,nonn
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AUTHOR
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Alan Sutcliffe (alansut(AT)ntlworld.com), Jun 05 2003
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EXTENSIONS
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Corrected and extended by T. D. Noe (noe(AT)sspectra.com), Oct 25 2006
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