a(n) = (n+2)*2^(2*n-1) - (n/2)*binomial(2*n,n).

Terms

a(0) =1a(1) =5a(2) =26a(3) =130a(4) =628a(5) =2954a(6) =13612a(7) =61716a(8) =276200a(9) =1223002a(10) =5367676a(11) =23383100a(12) =101215576a(13) =435712580a(14) =1866667448a(15) =7963424104a(16) =33846062544a(17) =143373104378a(18) =605518549660