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 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

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