A129027(n)/4.

Terms

a(0) =0a(1) =27a(2) =150a(3) =483a(4) =1188a(5) =2475a(6) =4602a(7) =7875a(8) =12648a(9) =19323a(10) =28350a(11) =40227a(12) =55500a(13) =74763a(14) =98658a(15) =127875a(16) =163152a(17) =205275a(18) =255078a(19) =313443a(20) =381300a(21) =459627a(22) =549450a(23) =651843a(24) =767928a(25) =898875a(26) =1045902a(27) =1210275a(28) =1393308a(29) =1596363