a(n) = K_3(n) = Sum_{k>=0} A090285(3,k)*2^k*binomial(n,k). a(n) = (4*n^3+30*n^2+56*n+15)/3.

Terms

a(0) =5a(1) =35a(2) =93a(3) =187a(4) =325a(5) =515a(6) =765a(7) =1083a(8) =1477a(9) =1955a(10) =2525a(11) =3195a(12) =3973a(13) =4867a(14) =5885a(15) =7035a(16) =8325a(17) =9763a(18) =11357a(19) =13115a(20) =15045a(21) =17155a(22) =19453a(23) =21947a(24) =24645a(25) =27555a(26) =30685a(27) =34043a(28) =37637a(29) =41475