OFFSET
0,2
LINKS
Michael De Vlieger, Table of n, a(n) for n = 0..1927
Andreas M. Hinz and Paul K. Stockmeyer, Precious Metal Sequences and Sierpinski-Type Graphs, J. Integer Seq., Vol 25 (2022), Article 22.4.8.
Index entries for linear recurrences with constant coefficients, signature (3,0,3,1).
FORMULA
a(n) = ((3 + sqrt(13)^n(11 + 3*sqrt(13))/13 + (3 - sqrt(13)^n(11 - 3*sqrt(13))/13)*2^(-1 - n) + 2(-1)^n/13;
a(n) = (-i)^n*Sum_{k=0..floor(n/2)} U(n-2k, 3i/2) where i = sqrt(-1).
G.f.: -1 / ( (1+x^2)*(x^2+3*x-1) ). - R. J. Mathar, Feb 14 2015
MATHEMATICA
LinearRecurrence[{3, 0, 3, 1}, {1, 3, 9, 30}, 30] (* Harvey P. Dale, Jun 16 2015 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Nov 15 2003
STATUS
approved