a(n) = Sum_{k=1..n} C(n,k) * sigma(k)^(n-k) for n>=1.
A251658
a(n) = Sum_{k=1..n} C(n,k) * sigma(k)^(n-k) for n>=1.
Terms
- a(0) =1a(1) =3a(2) =13a(3) =75a(4) =471a(5) =3273a(6) =26916a(7) =262027a(8) =2851375a(9) =33353433a(10) =422098711a(11) =5947420449a(12) =94264842933
External references
- oeis: A251658