a(n) = sigma_2(a(n-1)): sum of squares of divisors of a(n-1) with a(1)=2.
A138613
a(n) = sigma_2(a(n-1)): sum of squares of divisors of a(n-1) with a(1)=2.
Terms
- a(0) =2a(1) =5a(2) =26a(3) =850a(4) =943950
External references
- oeis: A138613
A138613
a(n) = sigma_2(a(n-1)): sum of squares of divisors of a(n-1) with a(1)=2.