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A062779
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a(n) = 2*n*(2*n)!.
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1
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0, 4, 96, 4320, 322560, 36288000, 5748019200, 1220496076800, 334764638208000, 115242726703104000, 48658040163532800000, 24728016011107368960000, 14890761641597746544640000, 10485577989291746525184000000
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OFFSET
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0,2
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LINKS
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FORMULA
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Sum_{n>=1} 1/a(n) = Chi(1) - gamma = A099284 - A001620, where Chi(x) is the hyperbolic cosine integral
Sum_{n>=1} (-1)^(n+1)/a(n) = gamma - Ci(1) = A001620 - A099282, where Ci(x) is the cosine integral. (End)
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MATHEMATICA
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a[n_] := 2*n*(2*n)!; Array[a, 14, 0] (* Amiram Eldar, Feb 14 2021 *)
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PROG
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(PARI) for(n=0, 22, print((2*n)*(2*n)!))
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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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