Cube of lower triangular matrix of A056857 (successive equalities in set partitions of n).

Terms

a(0) =1a(1) =3a(2) =1a(3) =12a(4) =6a(5) =1a(6) =57a(7) =36a(8) =9a(9) =1a(10) =309a(11) =228a(12) =72a(13) =12a(14) =1a(15) =1866a(16) =1545a(17) =570a(18) =120a(19) =15a(20) =1a(21) =12351a(22) =11196a(23) =4635a(24) =1140a(25) =180a(26) =18a(27) =1a(28) =88563a(29) =86457