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%I #19 Sep 13 2016 14:29:39
%S 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,
%T 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,
%U 6,5,4,3,20,12,6,5,2,20,15,10,5,4,3,20,15,12,10,5
%N Irregular triangle read by rows: strictly decreasing positive integer sequences in lexicographic order with the property that the sum of inverses equals one.
%H Peter Kagey, <a href="/A272083/b272083.txt">Table of n, a(n) for n = 1..1578</a> (All rows with first term less than or equal to 30.)
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Erd%C5%91s%E2%80%93Graham_problem">Erdős-Graham problem</a>.
%e First six rows:
%e [1] because 1/1 = 1.
%e [6, 3, 2] because 1/6 + 1/3 + 1/2 = 1.
%e [12, 6, 4, 2] because 1/12 + 1/6 + 1/4 + 1/2 = 1.
%e [15, 10, 3, 2] because 1/15 + 1/10 + 1/3 + 1/2 = 1.
%e [15, 12, 10, 4, 2] because 1/15 + 1/12 + 1/10 + 1/4 + 1/2 = 1.
%e [15, 12, 10, 6, 4, 3] because 1/15 + 1/12 + 1/10 + 1/6 + 1/4 + 1/3 = 1.
%Y Cf. A073546, A216975, A216993, A272020, A272036, A272081, A272082.
%K nonn,tabf
%O 1,2
%A _Peter Kagey_, Apr 19 2016
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