278920

Appears in sequences

• a(n) is the square of the n-th partial sum minus the n-th partial sum of the squares, divided by a(n-1), for all n>=1, starting with a(0)=1, a(1)=5.at n=16A087958
• Numbers k such that k and k+2 have the same number (A000005) and sum of divisors (A000203).at n=28A229254
• Number of permutations p of [n] such that p(p(i)) = i for all i or p(n+1-p(i)) = n+1-i for all i.at n=12A297708