371226240

Appears in sequences

• a(1) = 2, a(n) = sigma(a(n-1)).at n=22A007497
• a(n) = (n-1)!*(2^n-1) for n>=1, a(0)=0.at n=10A029767
• Numbers k for which k = sigma(sigma(x)) = sigma(sigma(y)) for some x and y such that k = x + y.at n=24A229953