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A006041
a(n+1) = (n^2 - 1)*a(n) + n + 1.
(Formerly M1949)
(Formerly M1949)
1
0, 2, 9, 76, 1145, 27486, 962017, 46176824, 2909139921, 232731193690, 23040388175321, 2764846581038532, 395373061088510089, 66422674262869694966, 12952421481259590518385, 2901342411802148276118256, 739842315009547810410155297, 213074586722749769398124725554, 68823091511448175515594286353961
OFFSET
1,2
REFERENCES
R. K. Guy, personal communication.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
FORMULA
Nearest integer to BesselI(1, 2)*(n-1)!*(n-1)!*n/(n-1), n>2.
MATHEMATICA
Join[{0, 2}, Table[Floor[BesselI[1, 2]*(n - 1)!*(n - 1)!*n/(n - 1)], {n, 3, 50}]] (* G. C. Greubel, Aug 16 2017 *)
RecurrenceTable[{a[1]==0, a[n+1]==(n^2-1)a[n]+n+1}, a, {n, 20}] (* Harvey P. Dale, May 16 2020 *)
PROG
(PARI) a(n) = if (n==1, 0, (n^2-2*n)*a(n-1) + n); \\ Michel Marcus, Aug 16 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
More terms from James Sellers, May 01 2000
STATUS
approved