A216365 - OEIS

%I #13 Sep 07 2012 03:25:01

%S 1,2,3,4,6,8,10,12,18,20,24,30,36,48,60,72,84,90,96,108,120,144,168,

%T 180,240,300,336,360,420,480,504,540,600,630,660,720,840,1008,1080,

%U 1200,1260,1440,1680,2100,2160,2520,3360,3780,3960,4200,4320,4620,4680,5040

%N Numbers n such that tau(n)*sigma(n) sets a new record.

%C Positions of record values in A064840.

%C Not identical to A067128; e.g. a(22) = 144 < 168 = A067128(22).

%H Charles R Greathouse IV and Donovan Johnson, <a href="/A216365/b216365.txt">Table of n, a(n) for n = 1..400</a> (first 268 terms from Charles R Greathouse IV)

%t lst = {}; k = 0; Do[n = DivisorSigma[0, i]*DivisorSigma[1, i]; If[n > k, AppendTo[lst, i]; k = n], {i, 7!}]; lst

%o (PARI) r=0;for(n=1,1e9,t=numdiv(n)*sigma(n);if(t>r,r=t;print1(n", "))) \\ _Charles R Greathouse IV_, Sep 05 2012

%Y Cf. A000005, A000203, A064840.

%K nonn

%O 1,2

%A _Arkadiusz Wesolowski_, Sep 05 2012