6093360

Appears in sequences

• Let S(n)=sigma(|n|)/2-n; sequence gives numbers n such that S(S(S(S(n))))=n. May be called {1,2}-sociable number of orders 1 or 2 or 4.at n=16A114529
• Denominator of Sum_{k=1..n} 1/sigma(k).at n=34A212718
• Denominator of Sum_{k=1..n} 1/sigma(k).at n=35A212718
• Numbers n such that there exists an x!=n that makes {n,n,x,x} an amicable multiset.at n=9A259306