A117859 Number of palindromes of length n (in base 7).

6, 6, 42, 42, 294, 294, 2058, 2058, 14406, 14406, 100842, 100842, 705894, 705894, 4941258, 4941258, 34588806, 34588806, 242121642, 242121642, 1694851494, 1694851494, 11863960458, 11863960458, 83047723206, 83047723206, 581334062442, 581334062442

Offset

1,1

Links

Table of n, a(n) for n=1..28.

Index entries for linear recurrences with constant coefficients, signature (0,7).

Formula

a(n) = 6*7^floor((n-1)/2).

a(n) = 7*a(n-2). G.f.: 6*x*(1+x)/(1-7*x^2). [Colin Barker, Jun 30 2012]

Mathematica

6*7^Floor[Range[0, 40]/2] (* Harvey P. Dale, Mar 23 2012 *)

Crossrefs

Cf. A050683.

Sequence in context: A278734 A279535 A125510 * A229159 A102901 A014435

Adjacent sequences: A117856 A117857 A117858 * A117860 A117861 A117862

Keyword

nonn,base,easy

Author

Martin Renner, May 02 2006

Extensions

More terms from Harvey P. Dale, Mar 23 2012

Status

approved