Numbers k such that k divides Sum_{i=1..k} gcd(k,i) = A018804(k).

Terms

a(0) =1a(1) =4a(2) =15a(3) =16a(4) =27a(5) =48a(6) =60a(7) =64a(8) =108a(9) =144a(10) =240a(11) =256a(12) =325a(13) =432a(14) =729a(15) =891a(16) =960a(17) =1008a(18) =1024a(19) =1200a(20) =1280a(21) =1296a(22) =1300a(23) =1728a(24) =1875a(25) =2916a(26) =3072a(27) =3125a(28) =3564a(29) =3645