OFFSET
1,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..800
Max Alekseyev, PARI scripts for various problems
Steven T. Dougherty and Esengül Saltürk, The neighbor graph of binary self-orthogonal codes, Adv. Math. Comm. (2024). See p. 16.
Index entries for linear recurrences with constant coefficients, signature (20,-64).
FORMULA
a(0)=0, a(1)=3; for n>1, a(n) = 20*a(n-1)-64*a(n-2). - T. D. Noe, Nov 30 2006
G.f.: 3*x / ( (16*x-1)*(4*x-1) ). - R. J. Mathar, Jul 23 2014
a(n) = (16^n-4^n)/4. - Vincenzo Librandi, Jul 25 2014
E.g.f.: exp(4*x)*(exp(12*x) - 1)/4. - Stefano Spezia, Aug 16 2024
MATHEMATICA
CoefficientList[Series[3/((16 x - 1) (4 x - 1)), {x, 0, 40}], x] (* Vincenzo Librandi, Jul 25 2014 *)
PROG
(Magma) [(16^n-4^n)/4: n in [1..20]]; // Vincenzo Librandi, Jul 25 2014
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Max Alekseyev, Jan 16 2006
STATUS
approved