4th power of the lower triangular normalized partition matrix.

Terms

a(0) =1a(1) =15a(2) =1a(3) =575a(4) =65a(5) =8a(6) =28759a(7) =4393a(8) =544a(9) =54a(10) =26454859a(11) =4978093a(12) =871144a(13) =95904a(14) =13500a(15) =35854425017a(16) =7684637159a(17) =1436323472a(18) =190754352a(19) =27540000a(20) =3087000a(21) =141598322427a(22) =34558204013a(23) =7383254904a(24) =1130247120a(25) =197499248a(26) =24685024