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A196506
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1*3*5 + 3*5*7 + 5*7*9 + .. (n terms).
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2
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0, 15, 120, 435, 1128, 2415, 4560, 7875, 12720, 19503, 28680, 40755, 56280, 75855, 100128, 129795, 165600, 208335, 258840, 318003, 386760, 466095, 557040, 660675, 778128, 910575, 1059240, 1225395, 1410360, 1615503, 1842240, 2092035
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OFFSET
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0,2
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COMMENTS
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All terms are multiples of 3.
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REFERENCES
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Jolley, Summation of Series, Dover (1961), eq (43) page 8.
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 0..10000
Index to sequences with linear recurrences with constant coefficients, signature (5,-10,10,-5,1).
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FORMULA
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a(n) = ((4*n^2-1)*(2*n+3)*(2*n+5)+15)/ 8 = sum_{i=1..n} (2*i-1)*(2*i+1)*(2*i+3).
G.f. -3*x*(5+15*x-5*x^2+x^3) / (x-1)^5 .
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PROG
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(MAGMA) [((4*n^2-1)*(2*n+3)*(2*n+5)+15)/ 8 : n in [0..30]]; // Vincenzo Librandi, Oct 05 2011
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CROSSREFS
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Cf. A061550 (first differences).
Sequence in context: A162321 A161875 A139615 * A027484 A185542 A126898
Adjacent sequences: A196503 A196504 A196505 * A196507 A196508 A196509
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KEYWORD
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nonn,easy
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AUTHOR
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R. J. Mathar, Oct 03 2011
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STATUS
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approved
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