A069084 Numbers n such that sigma(n)/tau(n) has denominator 5.

16, 48, 80, 81, 112, 176, 208, 240, 272, 336, 368, 405, 496, 528, 560, 567, 592, 624, 625, 656, 688, 720, 752, 784, 816, 848, 880, 891, 976, 1040, 1053, 1072, 1104, 1134, 1136, 1168, 1232, 1328, 1360, 1377, 1456, 1488, 1536, 1552, 1584, 1616, 1620, 1648

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Formula

n such that A057021(n)=5

Mathematica

Select[Range[500], Denominator[DivisorSigma[1, #]/DivisorSigma[0, #]] == 5 &] (* Amiram Eldar, Sep 08 2019 *)

Prog

(Magma) [n:n in [1..1700]|Denominator(SumOfDivisors(n)/#Divisors(n)) eq 5]; // Marius A. Burtea, Sep 08 2019

Crossrefs

Cf. A000005, A000203, A057021.

Sequence in context: A130897 A374589 A336595 * A084112 A050428 A134605

Adjacent sequences: A069081 A069082 A069083 * A069085 A069086 A069087

Keyword

easy,nonn

Author

Benoit Cloitre, Apr 05 2002

Status

approved