1700991

Appears in sequences

• Numbers n such that sigma(n) and d(n) are both harmonic (Ore) numbers.at n=25A071767
• a(1)=1 and a(2)=1; if a(n-1) + a(n-2) == 0 (mod n) then a(n) = (a(n-1) + a(n-2))/n else a(n) = a(n-1) + a(n-2).at n=37A330139