a(n) = Sum_{m=1..n} Sum_{k=1..m} C(2*k,k), where C(2*k,k) = (2*k)!/(k!)^2 = A000984(k).

A120278

a(n) = Sum_{m=1..n} Sum_{k=1..m} C(2*k,k), where C(2*k,k) = (2*k)!/(k!)^2 = A000984(k).

Terms

    a(0) =2a(1) =10a(2) =38a(3) =136a(4) =486a(5) =1760a(6) =6466a(7) =24042a(8) =90238a(9) =341190a(10) =1297574a(11) =4958114a(12) =19019254a(13) =73196994a(14) =282492254a(15) =1092867904a(16) =4236849774a(17) =16455966944a(18) =64020347914a(19) =249431257704a(20) =973100041934

External references