

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

Table of n, a(n) for n=0..9.
A. M. Cohen and D. E. Taylor, On a Certain Lie Algebra Defined by a Finite Group, American Math Monthly, volume 114, Number 7, AugSept 2007, pages 633638


FORMULA

a(n) = 2^(n^2)*8^n + Sum{k=1..n}{(1/2)^(k^2)*(1/8)^k}*2^(n^2)*8^n, n>=0.  Paolo P. Lava, Jul 30 2008


MATHEMATICA

a[0] = 1; a[n_] := a[n] = 2^(2*n + 1)*2*a[n  1] + 1 Table[a[n], {n, 0, 20}]


PROG

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


CROSSREFS

Sequence in context: A046731 A221268 A179157 * A130035 A032629 A232942
Adjacent sequences: A130446 A130447 A130448 * A130450 A130451 A130452


KEYWORD

nonn


AUTHOR

Roger L. Bagula, Aug 07 2007


EXTENSIONS

Definition and offset corrected by R. J. Mathar, Dec 05 2008
Name corrected by Michel Marcus, Sep 29 2017


STATUS

approved



