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A122752
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a(0) = 1; a(1) = 1; a(2) = 1; a(n) = (n-1)a(n-1)+(n-2)a(n-2)+(n-3)a(n-3) for n >= 3.
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1, 1, 1, 3, 12, 59, 352, 2455, 19592, 176033, 1758218, 19323213, 231721820, 3010799363, 42133608902, 631791578187, 10105884589152, 171760897623865, 3091106286704942, 58721542573721093, 1174269157320995428
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,4
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MAPLE
| a[0]:=1: a[1]:=1: a[2]:=1: for n from 3 to 20 do a[n]:=(n-1)*a[n-1]+(n-2)*a[n-2]+(n-3)*a[n-3] od: seq(a[n], n=0..20);
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MATHEMATICA
| a[0] = 1; a[1] = 1; a[2] = 1; a[n_] := a[n] = (n - 1)*a[n - 1] + (n - 2)*a[n - 2] + (n - 3)*a[n - 3] Table[a[n], {n, 0, 50}]
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CROSSREFS
| Sequence in context: A196710 A196711 A101054 * A020102 A201013 A065080
Adjacent sequences: A122749 A122750 A122751 * A122753 A122754 A122755
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KEYWORD
| nonn
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AUTHOR
| Roger Bagula (rlbagulatftn(AT)yahoo.com), Sep 21 2006
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EXTENSIONS
| Edited by N. J. A. Sloane (njas(AT)research.att.com), Oct 08 2006
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