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A224869 a(n) = n*( a(n-1)+1 ), initialized by a(1) = -1. 2
-1, 0, 3, 16, 85, 516, 3619, 28960, 260649, 2606500, 28671511, 344058144, 4472755885, 62618582404, 939278736075, 15028459777216, 255483816212689, 4598708691828420, 87375465144739999, 1747509302894800000, 36697695360790800021, 807349297937397600484 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..22.

FORMULA

a(n) +(-n-2)*a(n-1) +(2*n-1)*a(n-2) +(-n+2)*a(n-3)=0. - R. J. Mathar, Jul 28 2013

EXAMPLE

a(4) = 4*(a(3)+1)= 4*4 = 16.

MATHEMATICA

A224869[1] := -1; A224869[n_] := A224869[n - 1]n + n; Table[A224869[n], {n, 40}] (* Alonso del Arte, Jul 22 2013 *)

PROG

(Python)

a=-1

for n in range(2, 24):

  print str(a)+', ',

  a= n*(a+1)

CROSSREFS

Cf. A007526, A038156, A166554, A121662 (3rd column).

Sequence in context: A056369 A056360 A278681 * A163604 A151329 A026111

Adjacent sequences:  A224866 A224867 A224868 * A224870 A224871 A224872

KEYWORD

sign,easy

AUTHOR

Alex Ratushnyak, Jul 22 2013

STATUS

approved

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Last modified October 21 09:06 EDT 2018. Contains 316406 sequences. (Running on oeis4.)