Numbers k such that Sum_{j=1..k} sigma(j) is divisible by k, where sigma(j) = sum of divisors of j (A000203).

A056550

Numbers k such that Sum_{j=1..k} sigma(j) is divisible by k, where sigma(j) = sum of divisors of j (A000203).

Terms

    a(0) =1a(1) =2a(2) =8a(3) =11a(4) =17a(5) =63a(6) =180a(7) =259a(8) =818a(9) =2161a(10) =4441a(11) =8305a(12) =11998a(13) =694218a(14) =3447076a(15) =4393603a(16) =57402883a(17) =73459800a(18) =121475393a(19) =2068420025a(20) =5577330586a(21) =13320495021a(22) =35297649260a(23) =138630178659a(24) =988671518737

External references