a(n) = Sum_{k=0..n} k^4 * 2^(n-k) * binomial(n,k).

Terms

a(0) =0a(1) =1a(2) =20a(3) =189a(4) =1320a(5) =7785a(6) =41148a(7) =201285a(8) =929232a(9) =4100625a(10) =17452260a(11) =72098829a(12) =290521080a(13) =1146082041a(14) =4439303820a(15) =16923738645a(16) =63619864992a(17) =236206924065a(18) =867305334708