

A130449


a(0) = 1; a(n) = 4^(n+1)*a(n1)+1.


0




OFFSET

0,2


COMMENTS

The number of involutions in the group g_n D_{n+1} = G_n(operation) D_8.


LINKS



MATHEMATICA

a[0] = 1; a[n_] := a[n] = 2^(2*n + 1)*2*a[n  1] + 1 Table[a[n], {n, 0, 20}]
nxt[{n_, a_}]:={n+1, 4^(n+2) a+1}; NestList[nxt, {0, 1}, 10][[;; , 2]] (* Harvey P. Dale, Mar 13 2023 *)


PROG

(PARI) a(n) = if (n==0, 1, 4^(n+1)*a(n1)+1); \\ Michel Marcus, Sep 29 2017


CROSSREFS



KEYWORD

nonn


AUTHOR



EXTENSIONS

Definition and offset corrected by R. J. Mathar, Dec 05 2008


STATUS

approved



