a(n) = Sum_{k=0..n} k^6 * (-1)^k * 3^(n-k) * binomial(n,k).

Terms

a(0) =0a(1) =-1a(2) =58a(3) =-180a(4) =-1304a(5) =-2920a(6) =1008a(7) =34496a(8) =163840a(9) =525312a(10) =1285120a(11) =2241536a(12) =1124352a(13) =-12113920a(14) =-72052736a(15) =-282378240a(16) =-924581888a(17) =-2699493376a(18) =-7201751040a(19) =-17666670592a(20) =-39507722240a(21) =-77918109696a(22) =-121883328512a(23) =-78622228480a(24) =453588811776