Numerator of binomial(2n,n)/(2n).

Terms

a(0) =1a(1) =3a(2) =10a(3) =35a(4) =126a(5) =77a(6) =1716a(7) =6435a(8) =24310a(9) =46189a(10) =352716a(11) =676039a(12) =5200300a(13) =10029150a(14) =5170584a(15) =300540195a(16) =1166803110a(17) =756261275a(18) =17672631900a(19) =6892326441a(20) =89709645740a(21) =526024740930