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A004538
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3*n^2 + 3*n - 1.
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0
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-1, 5, 17, 35, 59, 89, 125, 167, 215, 269, 329, 395, 467, 545, 629, 719, 815, 917, 1025, 1139, 1259, 1385, 1517, 1655, 1799, 1949, 2105, 2267, 2435, 2609, 2789, 2975, 3167, 3365, 3569, 3779, 3995, 4217, 4445
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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LINKS
| Index to sequences with linear recurrences with constant coefficients, signature (3,-3,1).
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FORMULA
| a(n) = 5 * Sum[k^4,{k,1,n}] / Sum[k^2,{k,1,n}], n>0. a(n) = 5 * A000538(n) / A000330(n), n>0. - Alexander Adamchuk (alex(AT)kolmogorov.com), Apr 12 2006
a(n)=a(n-1)+6*n with a(0)=-1 [From Vincenzo Librandi, Nov 18 2010]
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MATHEMATICA
| Table[5*Sum[k^4, {k, 1, n}]/Sum[k^2, {k, 1, n}], {n, 1, 20}] - Alexander Adamchuk (alex(AT)kolmogorov.com), Apr 12 2006
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CROSSREFS
| First differences of A033445.
Cf. A028896, A003215, A077588, A000538, A000330.
Sequence in context: A078654 A083364 A026394 * A146231 A186029 A083048
Adjacent sequences: A004535 A004536 A004537 * A004539 A004540 A004541
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KEYWORD
| sign,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Eric T. Lane (ERICLANE(AT)UTCVM.UTC.EDU)
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