a(n) = sigma(2^(n-1)*a(n-1)) for n>1 with a(1)=1.

A180710

a(n) = sigma(2^(n-1)*a(n-1)) for n>1 with a(1)=1.

Terms

    a(0) =1a(1) =3a(2) =28a(3) =504a(4) =26520a(5) =3090528a(6) =690908400a(7) =432222336000

External references