Exponential generating function: exp(cosh(x)+2*x-1).

Terms

a(0) =1a(1) =2a(2) =5a(3) =14a(4) =44a(5) =152a(6) =575a(7) =2354a(8) =10379a(9) =48902a(10) =245240a(11) =1301984a(12) =7294589a(13) =42959282a(14) =265263185a(15) =1712168654a(16) =11528506124a(17) =80783015192a(18) =588097479635