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A196532
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a(n) = (n+1)!*(H(n)+H(n+1)), where H(n) = Sum_{k=1..n} 1/k is the n-th harmonic number.
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1
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1, 5, 20, 94, 524, 3408, 25416, 214128, 2012832, 20894400, 237458880, 2932968960, 39126516480, 560704273920, 8591147712000, 140160890419200, 2425888391270400, 44398288688947200, 856727919929548800
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OFFSET
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0,2
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COMMENTS
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Denominator of a(n)/n! is listed in A096620.
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LINKS
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FORMULA
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E.g.f.: (1+x - 2*log(1-x))/(1-x)^2.
a(n+3) = (3*n+8)*a(n+2) - (3*n+7)*(n+2)*a(n+1) + (n+1)*(n+2)^2*a(n). (End)
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MAPLE
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H:= n-> sum(1/k, k=1..n):seq((n+1)!*(H(n+1)+H(n)), n=0..20);
# Alternative:
f:= gfun:-rectoproc({a(n+3) = (3*n+8)*a(n+2)-(3*n+7)*(n+2)*a(n+1)+(n+1)*(n+2)^2*a(n), a(0)=1, a(1)=5, a(2)=20}, a(n), remember):
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MATHEMATICA
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Table[(n+1)!Total[HarmonicNumber[{n, n+1}]], {n, 0, 20}] (* Harvey P. Dale, Jul 17 2013 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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