a(n) = T(3n,n), where T is the array defined in A025564.

A025571

a(n) = T(3n,n), where T is the array defined in A025564.

Terms

    a(0) =1a(1) =3a(2) =19a(3) =140a(4) =1090a(5) =8749a(6) =71604a(7) =593997a(8) =4976785a(9) =42016975a(10) =356879250a(11) =3046096983a(12) =26105109424a(13) =224485080580

External references