Number of ways of refining the partition n^1 to get 1^n.

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =18a(5) =74a(6) =314a(7) =1614a(8) =8650a(9) =52794a(10) =337410a(11) =2373822a(12) =17327770a(13) =136539154a(14) =1115206818a(15) =9671306438a(16) =86529147794a(17) =816066328602