A279254 - OEIS

%I #22 Apr 05 2018 12:05:56

%S 1,2,4,6,8,10,20,30,40,60,100,120,180,200,240,260,300,390,520,600,780,

%T 1200,1300,1560,2340,2600,3120,3900,6630,7800,11700,13260,15600,22100,

%U 23400,26520,39780,44200,53040,66300,132600,198900,265200,397800,530400,663000,795600,928200

%N Positive integers that have a record number of divisors in Gaussian integers.

%C Indices of records in A062327.

%H Charles R Greathouse IV, <a href="/A279254/b279254.txt">Table of n, a(n) for n = 1..394</a>

%t With[{s = Array[DivisorSigma[0, #, GaussianIntegers -> True] &, 10^6]}, Map[FirstPosition[s, #][[1]] &, Union@ FoldList[Max, s]]] (* _Michael De Vlieger_, Apr 05 2018 *)

%o (PARI)

%o b(n)= \\ A062327

%o {

%o     my(r=1,f=factor(n));

%o     for(j=1,#f[,1], my(p=f[j,1],e=f[j,2]);

%o         if(p==2,r*=(2*e+1));

%o         if(p%4==1,r*=(e+1)^2);

%o         if(p%4==3,r*=(e+1));

%o     );

%o     return(r);

%o }

%o { my(r=0,t); for(n=1,10^6, t=b(n); if(t>r,r=t;print1(n,", "))); }

%o \\ _Joerg Arndt_, Dec 09 2016

%Y Subsequence of A097752.

%Y Cf. A062327, A002182 (factorization over the integers).

%K nonn

%O 1,2

%A _J. Lowell_, Dec 08 2016

%E Terms a(11) and beyond from _Joerg Arndt_, Dec 09 2016