a(n) = sigma(2n,n) for n>0 with a(0)=1.

A179504

a(n) = sigma(2n,n) for n>0 with a(0)=1.

Terms

    a(0) =1a(1) =3a(2) =21a(3) =252a(4) =4369a(5) =103158a(6) =3037530a(7) =106237176a(8) =4311810305a(9) =198756808749

External references