a(n) = 2*binomial(10*n+4,n)/(5*n+2).

A234527

a(n) = 2*binomial(10*n+4,n)/(5*n+2).

Terms

    a(0) =1a(1) =4a(2) =46a(3) =704a(4) =12341a(5) =234260a(6) =4685898a(7) =97274544a(8) =2075959314a(9) =45262862788

External references