OFFSET
0,2
COMMENTS
Row sums of number triangle A128414.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (-3,-4).
FORMULA
For n>0, a(n) = (1/r)^n + (1/s)^n, with r = (-3-i*sqrt(7))/8 and s = (-3+i*sqrt(7))/8 the roots of 4x^2+3x+1. - Ralf Stephan, Jul 20 2013
a(n) = -3*a(n-1) - 4*a(n-2) for n > 2. - Harry Richman, May 05 2020
MATHEMATICA
CoefficientList[Series[(1 - 4 x^2) / (1 + 3 x + 4 x^2), {x, 0, 40}], x] (* Vincenzo Librandi, Jul 20 2013 *)
LinearRecurrence[{-3, -4}, {1, -3, 1}, 40] (* Harvey P. Dale, Sep 24 2022 *)
CROSSREFS
KEYWORD
easy,sign
AUTHOR
Paul Barry, Mar 02 2007
STATUS
approved