This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A064048 #9 Mar 29 2022 15:10:29 %S A064048 1,1,3,1,1,2,2,4,5,9,9,2,2,2,4,5,5,1,1,1,1,1,1,5,5,5,5,7,7,2,2,2,2,2, %T A064048 2,4,4,4,4,1,1,1,1,1,3,3,3,4,4,4,4,4,4,4,4,6,6,6,6,4,4,4,4,4,4,4,4,4, %U A064048 4,6,6,1,1,1,1,1,1,1,1,3,3,3,3,6,6,6,6,6,6,2,2,2,2,2,2,2,2,2,2,2 %N A064048 Number of most frequently occurring numbers in the 1-to-n multiplication table. %H A064048 Branden Aldridge, <a href="/A064048/b064048.txt">Table of n, a(n) for n = 1..20000</a> %e A064048 In the 1-to-6 multiplication table, the most frequently occurring numbers (each occurring 4 times) are 6 and 12. Therefore a(6)=2. %t A064048 mfon[n_]:=Module[{x=SortBy[Tally[Times@@@Tuples[Range[n],2]], Last]}, Length[ Select[x,#[[2]]==x[[-1,2]]&]]]; Array[mfon,100] (* _Harvey P. Dale_, Oct 20 2012 *) %o A064048 (PARI) a(n)=my(v=List(),ct,s,r,t); for(a=1,n,for(b=1,n,listput(v,a*b))); s=Set(v); for(i=1,#s, t=sum(j=1,#v,v[j]==s[i]); if(t<r, next); if(t>r,ct=1;r=t, ct++)); ct \\ _Charles R Greathouse IV_, Feb 05 2022 %Y A064048 Cf. A064047, A057142, A057143, A057144. %K A064048 nonn %O A064048 1,3 %A A064048 Matthew Somerville (matthew.somerville(AT)trinity.oxford.ac.uk), Aug 24 2001