OFFSET
2,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 2..1000
S. Sundaram, The homology of partitions with an even number of blocks, J. Alg. Comb., 4 (1995), 69-92.
S. Sundaram, Plethysm, partitions with an even number of blocks and Euler numbers, DIMACS Series, Vol. 24 (1996), 171-198, Amer. Math. Soc.
Index entries for linear recurrences with constant coefficients, signature (5,-7,3).
FORMULA
a(n) = 2*3^(n-1)-2*n. - Vaclav Kotesovec, Nov 19 2012
From Colin Barker, Jun 20 2019: (Start)
G.f.: 2*x^2*(1 + x) / ((1 - x)^2*(1 - 3*x)).
a(n) = 5*a(n-1) - 7*a(n-2) + 3*a(n-3) for n>4.
(End)
MATHEMATICA
Table[2 3^(n-1) - 2 n, {n, 2, 30}] (* Vincenzo Librandi, May 03 2013 *)
PROG
(Magma) [2*3^(n-1)-2*n: n in [2..30]]; // Vincenzo Librandi, May 03 2013
(PARI) Vec(2*x^2*(1 + x) / ((1 - x)^2*(1 - 3*x)) + O(x^40)) \\ Colin Barker, Jun 20 2019
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Sheila Sundaram (sheila(AT)paris-gw.cs.miami.edu)
STATUS
approved