|
|
A062859
|
|
Size of smallest triangular multiplication table which contains some number n times.
|
|
7
|
|
|
1, 4, 12, 18, 30, 40, 60, 72, 90, 120, 140, 168, 180, 210, 252, 280, 315, 336, 360, 420, 504, 560, 630, 672, 720, 792, 840, 924, 990, 1008, 1155, 1232, 1260, 1320, 1386, 1540, 1584, 1680, 1848, 1980, 2016, 2310, 2376, 2520, 2640, 2772, 2970, 3024, 3080
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
|
|
EXAMPLE
|
a(4)=18 because the size-18 triangular multiplication table is the smallest to contain a particular number 4 times (namely the number A062858(4)=36).
|
|
PROG
|
(Python)
from itertools import count
from collections import Counter
c = Counter()
for m in count(1):
for i in range(1, m+1):
ij = i*m
c[ij] += 1
if c[ij]>=n:
|
|
CROSSREFS
|
The least such number is A062858(n).
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Ron A. Lalonde (ronronronlalonde(AT)hotmail.com), Jun 25 2001
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|