E.g.f.: Limit_{N->oo} [ Sum_{n>=0} (N + n*y)^(2*n) * (x/N)^n/n! ]^(1/N).

Terms

a(0) =1a(1) =1a(2) =0a(3) =1a(4) =4a(5) =0a(6) =1a(7) =12a(8) =42a(9) =0a(10) =1a(11) =24a(12) =216a(13) =752a(14) =0a(15) =1a(16) =40a(17) =660a(18) =5440a(19) =19360a(20) =0a(21) =1a(22) =60a(23) =1560a(24) =22320a(25) =178920a(26) =654912a(27) =0a(28) =1a(29) =84