A292431 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.

0, 6, 10, 12, 18, 20, 24, 30, 36, 40, 42, 48, 56, 60, 72, 84, 90, 108, 120, 144, 168, 180, 210, 240, 280, 300, 330, 336, 360, 420, 480, 504, 540, 600, 630, 660, 720, 840, 1008, 1080, 1200, 1260, 1440, 1560, 1680, 1980, 2100, 2160, 2310, 2340

Offset

1,2

Comments

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

Links

Table of n, a(n) for n=1..50.

Example

There are 4 unordered triples {a, b, c} of distinct positive integers from 1 to 10 such that a*b = c*10:
  {2, 5, 1}: 2*5 = 1*10 = 10;
  {4, 5, 2}: 4*5 = 2*10 = 20;
  {5, 6, 3}: 5*6 = 3*10 = 30;
  {5, 8, 4}: 5*8 = 4*10 = 40.
This is more than any n < 10, so 10 is in this sequence.

Crossrefs

Where records occur in A278648.

Cf. A292430.

Sequence in context: A066038 A242100 A125592 * A110085 A315126 A315127

Adjacent sequences: A292428 A292429 A292430 * A292432 A292433 A292434

Keyword

nonn

Author

Bobby Jacobs and Robert G. Wilson v, Sep 30 2017

Status

approved