a(0)=a(1)=1; thereafter a(n+1) = (1/n)*Sum_{k=0..n} a(k)^2 (a(n) is not always integral!).

A003504

a(0)=a(1)=1; thereafter a(n+1) = (1/n)*Sum_{k=0..n} a(k)^2 (a(n) is not always integral!).

Terms

    a(0) =1a(1) =1a(2) =2a(3) =3a(4) =5a(5) =10a(6) =28a(7) =154a(8) =3520a(9) =1551880a(10) =267593772160

External references