A292431 - OEIS

%I #33 Oct 06 2017 01:55:09

%S 0,6,10,12,18,20,24,30,36,40,42,48,56,60,72,84,90,108,120,144,168,180,

%T 210,240,280,300,330,336,360,420,480,504,540,600,630,660,720,840,1008,

%U 1080,1200,1260,1440,1560,1680,1980,2100,2160,2310,2340

%N Numbers n with record numbers of unordered triples {a, b, c} of distinct positive integers from 1 to n such that a*b = c*n.

%C Numbers n with record numbers of ordered triples {a, b, c} such that a*b = c*n with c < a < b < n.

%e There are 4 unordered triples {a, b, c} of distinct positive integers from 1 to 10 such that a*b = c*10:

%e   {2, 5, 1}: 2*5 = 1*10 = 10;

%e   {4, 5, 2}: 4*5 = 2*10 = 20;

%e   {5, 6, 3}: 5*6 = 3*10 = 30;

%e   {5, 8, 4}: 5*8 = 4*10 = 40.

%e This is more than any n < 10, so 10 is in this sequence.

%Y Where records occur in A278648.

%Y Cf. A292430.

%K nonn

%O 1,2

%A _Bobby Jacobs_ and _Robert G. Wilson v_, Sep 30 2017