Triangle giving a(n,k) = number of k-colored labeled graphs with n nodes.

Terms

a(0) =1a(1) =1a(2) =4a(3) =1a(4) =24a(5) =48a(6) =1a(7) =160a(8) =1152a(9) =1536a(10) =1a(11) =1440a(12) =30720a(13) =122880a(14) =122880a(15) =1a(16) =18304a(17) =1152000a(18) =10813440a(19) =29491200a(20) =23592960a(21) =1a(22) =330624a(23) =65630208a(24) =1348730880a(25) =7707033600a(26) =15854469120a(27) =10569646080a(28) =1a(29) =8488960