Numerator of Sum_{k=0..n} 1/binomial(n,k)^2.

Terms

a(0) =1a(1) =2a(2) =9a(3) =20a(4) =155a(5) =21a(6) =7441a(7) =3224a(8) =5697a(9) =3575a(10) =28523a(11) =27183a(12) =70357417a(13) =4661447a(14) =386395a(15) =8959408a(16) =10028928779a(17) =525966759a(19) =35051863075a(20) =847581175a(21) =709068173a(22) =62385202783a(23) =20340152122