a(n) = n! * Sum_{k=1..n} Sum_{d|k} (-1)^(d+1)/(d * (k/d)!).
A356401
a(n) = n! * Sum_{k=1..n} Sum_{d|k} (-1)^(d+1)/(d * (k/d)!).
Terms
- a(0) =1a(1) =2a(2) =9a(3) =25a(4) =150a(5) =841a(6) =6608a(7) =41945a(8) =437986a(9) =4364741a(10) =51640952a(11) =526219585a(12) =7319856206a(13) =102469338245
External references
- oeis: A356401