a(n) = A007678(2*n+1).

Terms

a(0) =0a(1) =1a(2) =11a(3) =50a(4) =154a(5) =375a(6) =781a(7) =1456a(8) =2500a(9) =4029a(10) =6175a(11) =9086a(12) =12926a(13) =17875a(14) =24129a(15) =31900a(16) =41416a(17) =52921a(18) =66675a(19) =82954a(20) =102050a(21) =124271a(22) =149941a(23) =179400a(24) =213004a(25) =251125a(26) =294151a(27) =342486a(28) =396550a(29) =456779