OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (5,-7,0,4).
FORMULA
a(n) = sum(sum((k+1)binomial(n-j, n-2j-k), k, 0, n-2j), j, 0, floor(n/2))
a(n) = (n-1)*2^n + F(n+3), with F(n) = A000045(n). - Ralf Stephan, May 09 2004
G.f.: (1-x)^2 / ((1-2*x)^2 * (1-x-x^2)). [Joerg Arndt, Aug 05 2013]
MATHEMATICA
Table[(n - 1) 2^n + Fibonacci[n + 3], {n, 0, 30}] (* Vincenzo Librandi, Aug 05 2013 *)
LinearRecurrence[{5, -7, 0, 4}, {1, 3, 9, 24}, 30] (* Harvey P. Dale, May 29 2021 *)
PROG
(Magma) [(n-1)*2^n + Fibonacci(n+3): n in [0..30]]; // Vincenzo Librandi, Aug 05 2013
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Feb 08 2003
STATUS
approved