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A086689
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Sum(i^2*t(i), i=1..n), where t = A000217.
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0
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1, 13, 67, 227, 602, 1358, 2730, 5034, 8679, 14179, 22165, 33397, 48776, 69356, 96356, 131172, 175389, 230793, 299383, 383383, 485254, 607706, 753710, 926510, 1129635, 1366911, 1642473, 1960777, 2326612, 2745112
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OFFSET
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1,2
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COMMENTS
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This sequence is related to A001296 by a(n) = n*A001296(n)-sum(A001296(i), i=0..n-1) with n>0. - Bruno Berselli, Jan 21 2013
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LINKS
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Table of n, a(n) for n=1..30.
Index to sequences with linear recurrences with constant coefficients, signature (6,-15,20,-15,6,-1).
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FORMULA
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a(n) = n(n+1)(n+2)(12n^2+9n-1)/120.
G.f. x*(1+7*x+4*x^2) / (x-1)^6 . - R. J. Mathar, Sep 15 2012
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EXAMPLE
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a(4) = 227 = 1^2*A000217(1)+2^2*A000217(2)+3^2*A000217(3)+4^2*A000217(4).
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PROG
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(PARI) t(n)=n*(n+1)/2 for(i=1, 30, print1(", "sum(j=1, i, j^2*t(i))))
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CROSSREFS
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Cf. A001296.
Sequence in context: A129746 A067863 A106975 * A141956 A137720 A199896
Adjacent sequences: A086686 A086687 A086688 * A086690 A086691 A086692
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KEYWORD
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nonn,easy
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AUTHOR
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Jon Perry, Jul 28 2003
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STATUS
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approved
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