a(n) = Sum_{1 <= x_1, x_2, x_3, x_4, x_5 <= n} ( n/gcd(x_1, x_2, x_3, x_4, x_5, n) )^2.

Terms

a(0) =1a(1) =125a(2) =2179a(3) =15997a(4) =78101a(5) =272375a(6) =823495a(7) =2047613a(8) =4765465a(9) =9762625a(10) =19487051a(11) =34857463a(12) =62748349a(13) =102936875a(14) =170182079a(15) =262094461a(16) =410338385a(17) =595683125a(18) =893871379a(19) =1249381697a(20) =1794395605a(21) =2435881375a(22) =3404824919a(23) =4461748727a(24) =6101640601a(25) =7843543625a(26) =10422071947