Partial sums of A051877.

Terms

a(0) =1a(1) =13a(2) =70a(3) =252a(4) =714a(5) =1722a(6) =3696a(7) =7260a(8) =13299a(9) =23023a(10) =38038a(11) =60424a(12) =92820a(13) =138516a(14) =201552a(15) =286824a(16) =400197a(17) =548625a(18) =740278a(19) =984676a(20) =1292830a(21) =1677390a(22) =2152800a(23) =2735460a(24) =3443895a(25) =4298931a(26) =5323878a(27) =6544720a(28) =7990312a(29) =9692584