Number of partitions of (n,n) into pairs (i,j) with i>0, j>=0.

Terms

a(0) =1a(1) =1a(2) =3a(3) =8a(4) =23a(5) =60a(6) =161a(7) =404a(8) =1011a(9) =2440a(10) =5804a(11) =13462a(12) =30798a(13) =69082a(14) =152862a(15) =333094a(16) =716781a(17) =1522534a(18) =3198011a(19) =6642274a(20) =13657417a(21) =27805917a(22) =56097811a(23) =112183092a(24) =222496203a(25) =437787036a(26) =854936195a(27) =1657526884a(28) =3191478236a(29) =6104379829