OFFSET
0,2
COMMENTS
Essentially the same as A095121. - R. J. Mathar, Mar 28 2012
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (3,-2).
FORMULA
Binomial transform of (1, 5, 3, 5, 3, 5, ...).
From Colin Barker, Mar 13 2014: (Start)
a(n) = 2^(2+n) - 2 for n > 0.
a(n) = 3*a(n-1) - 2*a(n-2) for n > 0.
G.f.: -(2*x^2-3*x-1) / ((x-1)*(2*x-1)). (End)
E.g.f.: 2*exp(x)*(2*exp(x) - 1) - 1. - Stefano Spezia, May 07 2023
EXAMPLE
a(3) = 30 = sum of row 3 terms of triangle A134066: (2 + 12 + 12 + 4).
a(3) = 30 = (1, 3, 3, 1) dot (1, 5, 3, 5) = (1 + 15 + 9 + 5).
MATHEMATICA
Join[{1}, LinearRecurrence[{3, -2}, {6, 14}, 50]] (* Vladimir Joseph Stephan Orlovsky, Feb 23 2012 *)
PROG
(PARI) Vec(-(2*x^2-3*x-1)/((x-1)*(2*x-1)) + O(x^100)) \\ Colin Barker, Mar 13 2014
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Gary W. Adamson, Oct 06 2007
STATUS
approved