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A158842
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a(n) = 1 + n*(n+1)*(n-1)/2.
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8
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1, 1, 4, 13, 31, 61, 106, 169, 253, 361, 496, 661, 859, 1093, 1366, 1681, 2041, 2449, 2908, 3421, 3991, 4621, 5314, 6073, 6901, 7801, 8776, 9829, 10963, 12181, 13486, 14881, 16369, 17953, 19636, 21421, 23311, 25309, 27418, 29641, 31981, 34441, 37024, 39733, 42571, 45541, 48646
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OFFSET
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0,3
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COMMENTS
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Binomial transform of the sequence 1, 0, 3, 3, 0, 0, 0, ... .
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LINKS
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FORMULA
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G.f.: 1-x*(-1-3*x^2+x^3) / (x-1)^4 . - R. J. Mathar, Nov 05 2011
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EXAMPLE
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a(4) = 31 = sum of row 4 terms of triangle A158841: (13 + 9 + 6 + 3).
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MAPLE
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1+n*(n+1)*(n-1)/2 ;
end proc:
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MATHEMATICA
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Table[1 + n*(n + 1)*(n - 1)/2, {n, 40}] (* and *) LinearRecurrence[{4, -6, 4, -1}, {1, 4, 13, 31}, 40] (* Vladimir Joseph Stephan Orlovsky, Feb 21 2012 *)
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PROG
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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