a(n) = numerator of Sum_{i=1..n} binomial(2n-i-1,i-1)/i.

Terms

a(0) =1a(1) =3a(2) =17a(3) =23a(4) =61a(5) =107a(6) =421a(7) =1103a(8) =5777a(9) =7563a(10) =19801a(11) =103681a(12) =135721a(13) =355323a(14) =1860497a(15) =2435423a(16) =6376021a(17) =11128427a(18) =43701901a(19) =114413063a(20) =599074577a(21) =784198803a(22) =2053059121a(23) =10749957121a(24) =14071876561a(25) =36840651123a(26) =192900153617