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%I #13 Apr 02 2017 00:28:17
%S 30,1260,1980,74256,1861860,603380175840
%N Numbers that occur 5 or more times in the triangle of denominators in Leibniz's Harmonic Triangle.
%C Of the first 6 terms the number 30 occurs 5 times, the others occur 6 times.
%C a(6) = 603380175840 is not an oblong number.
%e The number 30 appears 1 time in row 5 in the central position {5*C(4,2)}, 2 times in row 6 {6*C(5,1); 6*C(5,4)} and, trivially, 2 times in row 30 {30*C(29,0); 30*C(29,29)}.
%e The number 1260 appears 2 times in row 10 {10*C(9,4); 10*C(9,5)}, 2 times in row 36 {36*C(35,1); 36*C(35,34)} and, trivially, 2 times in row 1260 {1260*C(1259,0); 1260*C(1259,1259)}.
%Y Cf. A003506.
%K nonn,more
%O 1,1
%A _Gionata Neri_, May 22 2016
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