68694

Appears in sequences

• usigma(n) = 2n + d(n), where d(n) is the number of divisors of n.at n=26A063829
• a(n+1) = floor(a(n) * Sum_{k=0..n} 1/a(k)^s), where s = Sum_{k>=0} 1/a(k)^s and a(0)=1; s = 2.260568736857767...at n=15A080135
• Numbers k such that all the following properties hold: (i) k*reverse(k) is a square; (ii) k != reverse(k); (iii) k and reverse(k) are not both squares; and (iv) k and reverse(k) have the same number of digits.at n=26A082994
• Numbers k such that s(k) = 2*k, where s(k) is the sum of divisors of k that have a square factor (A162296).at n=31A322609