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A133754
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a(n) = n^5 - n^3.
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4
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0, 0, 24, 216, 960, 3000, 7560, 16464, 32256, 58320, 99000, 159720, 247104, 369096, 535080, 756000, 1044480, 1414944, 1883736, 2469240, 3192000, 4074840, 5142984, 6424176, 7948800, 9750000, 11863800, 14329224, 17188416, 20486760, 24273000, 28599360, 33521664
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OFFSET
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0,3
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LINKS
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FORMULA
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a(n) = 12*n*(2*binomial(n+2,4)- binomial(n+1,3)). - Gary Detlefs, Mar 25 2012
Sum_{n>=2} 1/a(n) = 5/4 - zeta(3). - Daniel Suteu, Feb 06 2017
G.f.: 24*x^2*(1 + 3*x + x^2)/(1-x)^6.
E.g.f.: x^2*(12 + 24*x + 10*x^2 + x^3)*exp(x). (End)
Sum_{n>=2} (-1)^n/a(n) = 3*zeta(3)/4 + 2*log(2) - 9/4. - Amiram Eldar, Jan 09 2021
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MAPLE
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MATHEMATICA
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PROG
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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