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Search: id:A033994
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| 2, 11, 32, 70, 130, 217, 336, 492, 690, 935, 1232, 1586, 2002, 2485, 3040, 3672, 4386, 5187, 6080, 7070, 8162, 9361, 10672, 12100, 13650, 15327, 17136, 19082, 21170, 23405, 25792, 28336, 31042, 33915, 36960, 40182, 43586, 47177, 50960, 54940
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OFFSET
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1,1
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REFERENCES
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A. H. Beiler, Recreations in the Theory of Numbers, Dover, N.Y., 1964, pp. 194-196.
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FORMULA
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a(n)=n(n+1)(5n+1)/6.
G.f.: (2*x+3*x^2)/(1-x)^4.
a(n) = A132121(n,1). - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Aug 12 2007
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MAPLE
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seq(add((k^2-n^2+(n+k)^2)/2, k=1..n), n=1..40); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Dec 01 2006
with(finance):seq(add(cashflows([n*k, k^2, 0], 0 ), k=0..n), n=1..45); # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Dec 22 2008]
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MATHEMATICA
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f[n_]:=5*n+2; s1=s2=0; lst={}; Do[a=f[n]; s1+=a; s2+=s1; AppendTo[lst, s2], {n, 0, 6!}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Jun 25 2009]
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PROGRAM
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(PARI) a(n)=n*(n+1)*(5*n+1)/6
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CROSSREFS
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Cf. A005476 and A016873.
Cf. A000330, A132124, A132112, A050409.
Adjacent sequences: A033991 A033992 A033993 this_sequence A033995 A033996 A033997
Sequence in context: A092761 A087933 A000755 this_sequence A023659 A094792 A031400
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KEYWORD
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easy,nonn
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AUTHOR
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Barry E. Williams, Dec 16 1999
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EXTENSIONS
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More terms from James A. Sellers (sellersj(AT)math.psu.edu), Jan 19 2000
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