a(n) = n! * Sum_{k=1..n} ( Sum_{d|k} (-1)^(k/d + 1) * d^2 ) /k.
A356391
a(n) = n! * Sum_{k=1..n} ( Sum_{d|k} (-1)^(k/d + 1) * d^2 ) /k.
Terms
- a(0) =1a(1) =5a(2) =35a(3) =206a(4) =1654a(5) =13524a(6) =130668a(7) =1262064a(8) =15027696a(9) =178581600a(10) =2407111200a(11) =33276182400a(12) =514020643200
External references
- oeis: A356391