|
|
A130449
|
|
a(0) = 1; a(n) = 4^(n+1)*a(n-1)+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(n-1)+1); \\ Michel Marcus, Sep 29 2017
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
Definition and offset corrected by R. J. Mathar, Dec 05 2008
|
|
STATUS
|
approved
|
|
|
|