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A122752 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. 0
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; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..21.

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);

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}]

RecurrenceTable[{a[0]==a[1]==a[2]==1, a[n]==(n-1)a[n-1]+(n-2)a[n-2]+ (n-3)a[n-3]}, a, {n, 50}] (* Harvey P. Dale, Jul 10 2012 *)

CROSSREFS

Sequence in context: A196711 A304788 A101054 * A020102 A277179 A201013

Adjacent sequences:  A122749 A122750 A122751 * A122753 A122754 A122755

KEYWORD

nonn

AUTHOR

Roger L. Bagula, Sep 21 2006

EXTENSIONS

Edited by N. J. A. Sloane, Oct 08 2006

STATUS

approved

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Last modified October 22 10:24 EDT 2019. Contains 328317 sequences. (Running on oeis4.)