a(n) = n! * Sum_{k=1..n} Sum_{d|k} 1/(d! * (k/d)!).
A356004
a(n) = n! * Sum_{k=1..n} Sum_{d|k} 1/(d! * (k/d)!).
Terms
- a(0) =1a(1) =4a(2) =14a(3) =64a(4) =322a(5) =2054a(6) =14380a(7) =116722a(8) =1060580a(9) =10636042a(10) =116996464a(11) =1411275650a(12) =18346583452a(13) =256869465610
External references
- oeis: A356004