OFFSET
0,4
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..400
FORMULA
a(n) = n!*b(n), where b(n) = (n^2 - 2*n - 1)*b(n) and b(0) = b(1) = 1.
a(n) = ((n-1)^2 - 2)*a(n-2) with a(0) = a(1) = 1. - G. C. Greubel, Jul 20 2021
MATHEMATICA
b[n_]:= b[n]= If[n<2, 1, ((n-1)^2 -2)*b[n-2]/(n*(n-1))];
Table[b[n]*n!, {n, 0, 30}]
PROG
(Magma)
function a(n)
if n lt 2 then return 1;
else return ((n-1)^2 -2)*a(n-2);
end if; return a;
end function;
[a(n): n in [0..30]]; // G. C. Greubel, Jul 20 2021
(Sage)
def a(n): return 1 if (n<2) else ((n-1)^2 -2)*a(n-2)
[a(n) for n in (0..30)] # G. C. Greubel, Jul 20 2021
CROSSREFS
KEYWORD
sign
AUTHOR
Roger L. Bagula, Sep 24 2006
EXTENSIONS
Edited by N. J. A. Sloane, Oct 01 2006
Edited by G. C. Greubel, Jul 20 2021
STATUS
approved