A272083 - OEIS

A272083

Irregular triangle read by rows: strictly decreasing positive integer sequences in lexicographic order with the property that the sum of inverses equals one.

1, 6, 3, 2, 12, 6, 4, 2, 15, 10, 3, 2, 15, 12, 10, 4, 2, 15, 12, 10, 6, 4, 3, 18, 9, 3, 2, 18, 12, 9, 4, 2, 18, 12, 9, 6, 4, 3, 18, 15, 10, 9, 6, 2, 18, 15, 12, 10, 9, 4, 3, 20, 5, 4, 2, 20, 6, 5, 4, 3, 20, 12, 6, 5, 2, 20, 15, 10, 5, 4, 3, 20, 15, 12, 10, 5

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Peter Kagey, Table of n, a(n) for n = 1..1578 (All rows with first term less than or equal to 30.)

Wikipedia, Erdős-Graham problem.

EXAMPLE

First six rows:

[1] because 1/1 = 1.

[6, 3, 2] because 1/6 + 1/3 + 1/2 = 1.

[12, 6, 4, 2] because 1/12 + 1/6 + 1/4 + 1/2 = 1.

[15, 10, 3, 2] because 1/15 + 1/10 + 1/3 + 1/2 = 1.