A065390 Peak values reached by A062402 at the sites listed in A065389.

1, 3, 7, 12, 18, 28, 31, 39, 42, 56, 72, 91, 96, 98, 168, 195, 252, 280, 312, 360, 372, 392, 546, 576, 744, 840, 864, 992, 1092, 1170, 1344, 1512, 1680, 1860, 1872, 2016, 2240, 2418, 2880, 3224, 3600, 3844, 4320, 4368, 4914, 5082, 5952, 6045, 6552, 7440

Offset: 1

Author

Labos Elemer, Nov 05 2001

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..958 (terms 1..500 from Harry J. Smith)

Crossrefs

Cf. A062402, A000203, A000010, A065389, A065391, A065392, A065393, A065394.

Programs

Mathematica

a=0; s=0; Do[s=DivisorSigma[1, EulerPhi[n]]; If[s>a, a=s; Print[s]], {n, 1, 10000}]
(* Second program: *)
Union@ FoldList[Max, Array[DivisorSigma[1, EulerPhi[#]] &, 2200]] (* Michael De Vlieger, Jun 19 2018 *)

PARI

{ n=r=0; for (m=1, 10^9, x=sigma(eulerphi(m)); if (x > r, r=x; write("b065390.txt", n++, " ", x); if (n==500, return)) ) } \\ Harry J. Smith, Oct 18 2009

Formula

a(n) = A062402(A065389(n)). - Amiram Eldar, Mar 22 2025