A273016 Ramanujan's largely composite numbers having 5 as the greatest prime divisor.

10, 20, 30, 60, 90, 120, 180, 240, 360, 480, 540, 600, 720, 1080, 1440, 2160, 4320

Offset: 1

Author

Vladimir Shevelev and Peter J. C. Moses, May 13 2016

Keywords

• nonn
• fini
• full

Comments

By the theorem in comment in A273015, the sequence is finite.

Crossrefs

Cf. A067128, A273015.

Programs

Mathematica

a = {}; b = {0}; Do[If[# >= Max@ b, AppendTo[a, k] && AppendTo[b, #]] &@ DivisorSigma[0, k], {k, 10^7}]; Select[a, FactorInteger[#][[-1, 1]] == 5 &] (* Michael De Vlieger, May 13 2016 *)