a(n) = A064835(n)/2.

Terms

a(0) =0a(1) =0a(2) =1a(3) =5a(4) =22a(5) =60a(6) =135a(7) =261a(8) =460a(9) =752a(10) =1165a(11) =1725a(12) =2466a(13) =3420a(14) =4627a(15) =6125a(16) =7960a(17) =10176a(18) =12825a(19) =15957a(20) =19630a(21) =23900a(22) =28831a(23) =34485a(24) =40932a(25) =48240a(26) =56485a(27) =65741a(28) =76090a(29) =87612