A193988 Numbers n such that sigma_2(n) > sigma_2(k) for all k < n.

1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 22, 24, 28, 30, 32, 34, 36, 40, 42, 44, 46, 48, 52, 54, 56, 60, 64, 66, 70, 72, 78, 80, 84, 90, 96, 100, 102, 108, 114, 120, 126, 132, 138, 140, 144, 150, 156, 162, 168, 180, 192, 198, 204, 210, 216, 228

Offset: 1

Author

T. D. Noe, Aug 17 2011

Keywords

• nonn

Comments

Where record values of sigma_2(n) occur. Records transform of A001157.

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1000 from T. D. Noe)

Crossrefs

Cf. A001157, A002093 (highly abundant numbers), A193989.

Programs

Mathematica

mx = 0; t = {}; Do[u = DivisorSigma[2, n]; If[u > mx, mx = u; AppendTo[t, n]], {n, 1000}]; t
DeleteDuplicates[Table[{n,DivisorSigma[2,n]},{n,1000}],GreaterEqual[#1[[2]],#2[[2]]]&][[All,1]] (* Harvey P. Dale, May 14 2022 *)