a(n) = Sum_{k=0..n-2} T(n,k) * T(n,k+2), with T given by A026386.

A026953

a(n) = Sum_{k=0..n-2} T(n,k) * T(n,k+2), with T given by A026386.

Terms

    a(0) =1a(1) =8a(2) =41a(3) =272a(4) =1168a(5) =7428a(6) =30302a(7) =189808a(8) =759101a(9) =4724160a(10) =18728841a(11) =116207424a(12) =458829051a(13) =2842936320a(14) =11203933255a(15) =69378730880a(16) =273211969075

External references