a(n) = Sum{0<=k<=n} binomial(n+k, n-k) * k! / (floor(k/2)! * floor((k+2)/2)!).

A190908

a(n) = Sum{0<=k<=n} binomial(n+k, n-k) * k! / (floor(k/2)! * floor((k+2)/2)!).

Terms

    a(0) =1a(1) =2a(2) =5a(3) =15a(4) =49a(5) =163a(6) =549a(7) =1875a(8) =6477a(9) =22571a(10) =79213a(11) =279631a(12) =991985a(13) =3533707a(14) =12632909a(15) =45301795a(16) =162890781a(17) =587091795a(18) =2120442517a(19) =7672891151a(20) =27811187377a(21) =100956896179a(22) =366983328885

External references