login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A275825 Third-order sequence with non-constant coefficients: a(n) = (n-3)*a(n-1) + (n-1)*a(n-3); a(0) = a(1) = a(2) = 1. 1
1, 1, 1, 2, 5, 14, 52, 238, 1288, 8144, 59150, 486080, 4464304, 45352840, 505200280, 6124903616, 80304039608, 1132339758992, 17089219746352, 274872988654576, 4694355262548640, 84840179120802560, 1617735736056994736, 32457990536915964800, 683569125395013719680 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Robert Israel, Table of n, a(n) for n = 0..450

FORMULA

a(n) ~ c * n^(n-5/2) / exp(n), where c = 35.33624296996624315241349866820530476... . - Vaclav Kotesovec, Oct 04 2016

MAPLE

f:= gfun:-rectoproc({a(n) = (n-3)*a(n-1) + (n-1)*a(n-3), a(0) = 1, a(1) = 1, a(2) = 1}, a(n), remember):

map(f, [$0..30]); # Robert Israel, Nov 08 2016

MATHEMATICA

RecurrenceTable[{a[n+1]==(n-2)*a[n]+n*a[n-2], a[0]==1, a[1]==1, a[2]==1}, a, {n, 0, 15}]

PROG

(C) int seq(int n) {int v = 1; if(n <= 2) {v = 1; } else {v = (n-3)*seq(n-1) + (n-1)*seq(n-3); }return v; }

CROSSREFS

Cf. A000930, A000931.

Sequence in context: A000679 A266932 A243787 * A081439 A052649 A267561

Adjacent sequences:  A275822 A275823 A275824 * A275826 A275827 A275828

KEYWORD

nonn

AUTHOR

Christopher C. Capobianco, Sep 13 2016

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified August 8 02:45 EDT 2020. Contains 336290 sequences. (Running on oeis4.)