A064048 Number of most frequently occurring numbers in the 1-to-n multiplication table.

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, 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, 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

Offset

1,3

Links

Branden Aldridge, Table of n, a(n) for n = 1..20000

Example

In the 1-to-6 multiplication table, the most frequently occurring numbers (each occurring 4 times) are 6 and 12. Therefore a(6)=2.

Mathematica

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 *)

Prog

(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

Crossrefs

Cf. A064047, A057142, A057143, A057144.

Sequence in context: A352935 A364757 A204253 * A336218 A016464 A245570

Adjacent sequences: A064045 A064046 A064047 * A064049 A064050 A064051

Keyword

nonn

Author

Matthew Somerville (matthew.somerville(AT)trinity.oxford.ac.uk), Aug 24 2001

Status

approved