A164334 Quartic recurrence sequence a(0) = 1, a(n) = n*a(n-1)^4.

1, 1, 2, 48, 21233664, 1016411962239204484414785454080

Offset: 0

Author

David Willingham (D.Willingham(AT)wmin.ac.uk), Aug 13 2009

Keywords

• nonn

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

Crossrefs

Quartic extension of A052129 and A123851.

Programs

Mathematica

nxt[{n_,a_}]:={n+1,(n+1)a^4}; NestList[nxt,{0,1},5][[All,2]] (* Harvey P. Dale, Dec 19 2016 *)

PARI

a(n) = if (n==0, 1, n*a(n-1)^4); \\ Michel Marcus, Sep 14 2017

Formula

a(0) = 1, a(n) = n*a(n-1)^4.