Pillai's arithmetical function: sum of gcd(k, n) for 1 <= k <= n.
1, 3, 5, 8, 9, 15, 13, 20, 21, 27, 21, 40, 25, 39, 45, 48, 33, 63, 37, 72, 65, 63, 45, 100
1 seqfan posts
Mon Sep 6 05:40:16 CEST 2010 [seqfan] Re: Number of solutions of a*b + c*d + ... + y*z = 0 (mod n)