a(2*n) = Sum_{k=0..n-1} binomial(2*n,k) binomial(2*n-1-k, n-1-k). a(2*n+1) = (Sum_{k=0..n} binomial(2*n+1,k) binomial(2*n-k, n-k)) - binomial(2*n-1, n).

A359067

a(2*n) = Sum_{k=0..n-1} binomial(2*n,k) binomial(2*n-1-k, n-1-k). a(2*n+1) = (Sum_{k=0..n} binomial(2*n+1,k) binomial(2*n-k, n-k)) - binomial(2*n-1, n).

Terms

    a(0) =0a(1) =1a(2) =4a(3) =7a(4) =28a(5) =49a(6) =199a(7) =351a(8) =1436a(9) =2561a(10) =10499a(11) =18943a(12) =77617a(13) =141569a(14) =579149a(15) =1066495a(16) =4354780a(17) =8085505a(18) =32954635a(19) =61616127a(20) =250713893a(21) =471556097a(22) =1915928117a(23) =3621830655a(24) =14696701553a(25) =27902803969a(26) =113099318869a(27) =215530668031a(28) =872780984131

External references