E.g.f.: exp( Sum_{n>=1} ( Product_{k=1..n} sigma(k) ) * x^n/n! ).

A294343

E.g.f.: exp( Sum_{n>=1} ( Product_{k=1..n} sigma(k) ) * x^n/n! ).

Terms

    a(0) =1a(1) =1a(2) =4a(3) =22a(4) =178a(5) =1570a(6) =18808a(7) =230980a(8) =3505468a(9) =57144700a(10) =1068295600a(11) =20546428360a(12) =461887088728

External references