OFFSET
0,3
COMMENTS
Number of different orderings for n-input trees in a Free Quaternary Decision Diagram.
The next term has 121 digits. - Harvey P. Dale, Dec 19 2016
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..7
FORMULA
a(0) = 1, a(n) = n*a(n-1)^4.
MATHEMATICA
nxt[{n_, a_}]:={n+1, (n+1)a^4}; NestList[nxt, {0, 1}, 5][[All, 2]] (* Harvey P. Dale, Dec 19 2016 *)
PROG
(PARI) a(n) = if (n==0, 1, n*a(n-1)^4); \\ Michel Marcus, Sep 14 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
David Willingham (D.Willingham(AT)wmin.ac.uk), Aug 13 2009
STATUS
approved