A330006 - OEIS

%I #9 Nov 27 2019 05:31:56

%S 1,2,3,4,6,10,12,18,24,30,42,54,60,78,84,90,114,120,150,168,180,210,

%T 270,294,300,330,390,420,510,546,570,630,750,780,840,990,1050,1170,

%U 1260,1470,1650,1680,1890,2100,2310,2730,3150,3360,3570,3990,4290,4620,5250

%N Numbers m such that psi(m) > psi(k) for all k < m, where psi is the Dedekind psi function (A001615).

%H Amiram Eldar, <a href="/A330006/b330006.txt">Table of n, a(n) for n = 1..808</a> (terms below 10^11)

%F A001615(a(n)) = A210523(n).

%e The first 6 values of the psi function are 1, 3, 4, 6, 6, 12. The record values, 1, 3, 4, 6, 12 are at positions 1, 2, 3, 4, 6.

%t psi[1] = 1; psi[n_] := n * Times @@ (1 + 1/FactorInteger[n][[;; , 1]]); seq = {}; pmax = 0; Do[p = psi[n]; If[p > pmax, pmax = p; AppendTo[seq, n]], {n, 1, 10^5}]; seq

%Y Cf. A001615, A210523 (record values).

%K nonn

%O 1,2

%A _Amiram Eldar_, Nov 26 2019