71085

Appears in sequences

• a(0) = 0, a(n) = smallest composite k such that phi(k + 2^n) = phi(k) + 2^n; also cototient(k + 2^n) = cototient(k).at n=20A063104
• a(n) = n*(n+1)*(7*n^2 - n - 4)/4.at n=14A172077