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A350855
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a(0) = 1, a(n) = (n+1)*a(n-1) + (n-2).
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0
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1, 1, 3, 13, 67, 405, 2839, 22717, 204459, 2044597, 22490575, 269886909, 3508529827, 49119417589, 736791263847, 11788660221565, 200407223766619, 3607330027799157, 68539270528183999, 1370785410563679997, 28786493621837279955, 633302859680420159029, 14565965772649663657687
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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) ~ (6-2e)*(n+1)!.
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EXAMPLE
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a(1) = (1+1)*a(0) + (1-2) = 2-1 = 1.
a(2) = (2+1)*a(1) + (2-2) = 3.
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MATHEMATICA
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Nest[Append[#1, (#2 + 1) #1[[-1]] + (#2 - 2)] & @@ {#, Length@ #} &, {1}, 20] (* Michael De Vlieger, Jan 19 2022 *)
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PROG
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(PARI) a(n) = if (n, (n+1)*a(n-1) + (n-2), 1); \\ Michel Marcus, Jan 19 2022
(Python)
terms = [1]
for n in range(1, 20):
terms.append((n+1)*terms[-1]+n-2)
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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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