a(1) = 1, a(m+1) = Sum_{k=1..m} lcm(m, a(k)).

Terms

a(0) =1a(1) =1a(2) =4a(3) =18a(4) =48a(5) =360a(6) =450a(7) =6174a(8) =27000a(9) =34200a(10) =93250a(11) =1776566a(12) =11293824a(13) =172014648a(14) =1296688778a(15) =20393895570a(16) =173895132784