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 A130449 a(0) = 1; a(n) = 4^(n+1)*a(n-1)+1. 0
 1, 17, 1089, 278785, 285475841, 1169309044737, 19157959388971009, 1255536026515604045825, 329131236134906506988748801, 345119115061395725472234262757377 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS The number of involutions in the group g_n D_{n+1} = G_n(operation) D_8. LINKS A. M. Cohen and D. E. Taylor, On a Certain Lie Algebra Defined by a Finite Group, American Math Monthly, volume 114, Number 7, Aug-Sept 2007, pages 633-638 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 = 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(n-1)+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

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Last modified July 7 14:14 EDT 2020. Contains 335495 sequences. (Running on oeis4.)