3655680

Appears in sequences

• Numbers n such that denominator(sigma(sigma(n))/n) = denominator(sigma(sigma(s))/s) where s = sigma(n).at n=31A275321
• a(n) = 2^(n-7)*(n^4 - 6*n^3 + 59*n^2 - 54*n)/3.at n=15A384506