Harmonic seed numbers.

Terms

a(0) =1a(1) =6a(2) =28a(3) =270a(4) =496a(5) =672a(6) =1638a(7) =6200a(8) =8128a(9) =18620a(10) =30240a(11) =32760a(12) =173600a(13) =1089270a(14) =2229500a(15) =2457000a(16) =4713984a(17) =6051500a(18) =8506400a(19) =17428320a(20) =23088800a(21) =29410290a(22) =33550336a(23) =45532800a(24) =52141320a(25) =81695250a(26) =115048440a(27) =142990848a(28) =255428096