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%I #7 Mar 12 2017 15:12:49
%S 1,4,18,168,3648,298165,159628076
%N Number of nondecreasing sequences of 2n positive integers with reciprocals adding up to n (1 <= n).
%C Conjecture: A156869(2n + m, n + m) = a(n) if and only if m >= 0.
%e For n = 2, the a(2) = 4 sequences are (1, 2, 3, 6), (1, 2, 4, 4), (1, 3, 3, 3) and (2, 2, 2, 2) because 1/1 + 1/2 + 1/3 + 1/6 = 1/1 + 1/2 + 1/4 + 1/4 = 1/1 + 1/3 + 1/3 + 1/3 = 1/2 + 1/2 + 1/2 + 1/2 = 2.
%Y a(n) = A156869(2n, n).
%K more,nonn
%O 1,2
%A _Jens Voß_, Feb 17 2009
%E a(6) from _M. F. Hasler_, Feb 21 2009
%E a(7) from _Max Alekseyev_, Jan 04 2017