OFFSET
0,1
LINKS
Michael De Vlieger, Table of n, a(n) for n = 0..363
Joël Gay, Representation of Monoids and Lattice Structures in the Combinatorics of Weyl Groups, Doctoral Thesis, Discrete Mathematics [cs.DM], Université Paris-Saclay, 2018.
Z. Li, Z. Li and Y. Cao, Enumeration of symplectic and orthogonal injective partial transformations, Discrete Math., 306 (2006), 1781-1787.
MATHEMATICA
Array[Sum[Binomial[#, i]^2*i!*4^i, {i, 0, #}] + 2^#*#! &, 18, 0] (* Michael De Vlieger, Nov 28 2018 *)
PROG
(PARI) a(n) = 2^n*n! + sum(i=0, n, binomial(n, i)^2*i!*4^i); \\ Michel Marcus, May 31 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Aug 11 2006
STATUS
approved