12942720

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=25A114529
• Triangular array read by rows: T(n,k) is the number of functions f:{1,2,...,n}->{1,2,...,n} with a height of k; n>=1, 0<=k<=n-1.at n=42A216242
• Numbers n such that there exists an x!=n that makes {n,n,x,x} an amicable multiset.at n=18A259306
• Number of n-step excursions on the 9-dimensional f.c.c. lattice.at n=5A271672