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A155965
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a(n) = n*(n^2+4).
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4
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0, 5, 16, 39, 80, 145, 240, 371, 544, 765, 1040, 1375, 1776, 2249, 2800, 3435, 4160, 4981, 5904, 6935, 8080, 9345, 10736, 12259, 13920, 15725, 17680, 19791, 22064, 24505, 27120, 29915, 32896, 36069, 39440, 43015, 46800, 50801, 55024, 59475, 64160
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OFFSET
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0,2
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COMMENTS
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The identity (n^3+4*n)^2 + (2*n^2+8)^2 = (n^2+4)^3 can be written as a(n)^2 + A155966(n)^2 = A087475(n)^3.
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LINKS
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FORMULA
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a(n) = 4*a(n-1) - 6*a(n-2) +4*a(n-3) - a(n-4) for n>3. - Vincenzo Librandi, May 03 2014
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MATHEMATICA
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CoefficientList[Series[x (5 - 4 x + 5 x^2)/(1 - x)^4, {x, 0, 60}], x] (* Vincenzo Librandi, May 03 2014 *)
LinearRecurrence[{4, -6, 4, -1}, {0, 5, 16, 39}, 50] (* Harvey P. Dale, Jan 23 2019 *)
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PROG
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(Sage) [lucas_number1(4, n, -2) for n in range(0, 41)] # Zerinvary Lajos, May 16 2009
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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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STATUS
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approved
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