a(n) = Sum_{i=0..n-1} a(i) * a(n-i), a(0) = 1, a(1) = 5.

Terms

a(0) =1a(1) =5a(2) =5a(3) =30a(4) =80a(5) =405a(6) =1505a(7) =7255a(8) =31155a(9) =149455a(10) =688655a(11) =3334880a(12) =15965130a(13) =78294155a(14) =383599455a(15) =1903940030a(16) =9474093880a(17) =47514889255a(18) =239112929655