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A143963
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Binomial transform of A012245 (characteristic function of factorial numbers).
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1
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0, 1, 3, 6, 10, 15, 22, 35, 64, 129, 265, 528, 1002, 1807, 3108, 5125, 8144, 12529, 18735, 27322, 38970, 54495, 74866, 101223, 134897, 177450, 230906, 299313, 397621, 594210, 1188015, 3366352, 11425020, 39675229, 132473639, 418849690, 1253626158, 3564792787
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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) = Sum_{k=1..n} C(n,k)*A012245(k).
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EXAMPLE
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a(6) = [6,15,20,15,6,1]*[1,1,0,0,0,1] = 6+15+1 = 22.
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MAPLE
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a:= proc(n) local k, i, s; s:=0; k:=1; i:=1; while k<=n do s:= s+ binomial(n, k); i:=i+1; k:=k*i; od; s; end: seq(a(n), n=0..40);
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PROG
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(Python)
from math import comb
c, i, s = 1, 1, 0
while (c:=c*i) <= n:
s += comb(n, c)
i += 1
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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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