login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A108189 a(n) = (n-1)*(a(n-2)+a(n-3)) 3
0, 1, 1, 3, 8, 20, 66, 196, 688, 2358, 8840, 33506, 134376, 550498, 2350348, 10273110, 46413536, 214598786, 1020359628, 4959234118, 24699168280, 125571468666, 652484852756, 3456224649758, 18673351714128, 102717737562850 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,4
COMMENTS
Recurrence is similar to A000166 or A000931.
LINKS
FORMULA
a(n) ~ (3/4)*sqrt(2) * exp(sqrt(n)-n/2-1/4)*n^(n/2-1/2) * (1-53/(24*sqrt(n))). - Vaclav Kotesovec, Dec 28 2012
MAPLE
f:= gfun:-rectoproc({a(n) = (n-1)*(a(n-2)+a(n-3)), a(1)=0, a(2)=1, a(3)=1}, a(n), remember):
map(f, [$1..40]); # Robert Israel, Feb 20 2017
MATHEMATICA
F[1] = 0; F[2] = 1; F[3] = 1; F[n__] := F[n] = (n - 1)*( F[n - 2] + F[n - 3]) a = Table[F[n], {n, 1, 25}]
CROSSREFS
Sequence in context: A009436 A354519 A302674 * A148768 A110861 A027320
KEYWORD
nonn
AUTHOR
Roger L. Bagula, Jun 14 2005
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 28 05:02 EDT 2024. Contains 371235 sequences. (Running on oeis4.)