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%I #40 Aug 03 2022 22:27:11
%S 1,3,6,10,15,22,33,44,59,76,101,125,158
%N Minimum m such that there exists an n-row subtractive triangle with distinct integers in 1..m.
%C In an n-row subtractive triangle, there are n-i+1 integers in the i-th row. The integers in the first row are arbitrary. From the next row, the integers are the absolute difference between adjacent integers in the previous row.
%H Chyanog, <a href="http://bbs.emath.ac.cn/thread-4977-1-1.html">A Chinese web page where the problem was posed</a>.
%H International Mathematical Olympiad, <a href="https://www.imo-official.org/problems.aspx">Problem 3 of IMO 2018</a>.
%H Denis Cazor, <a href="/A226239/a226239.pdf">Algorithme en Français</a>
%H Denis Cazor, <a href="/A226239/a226239_1.pdf">Algorithm in English</a>
%e a(6)=22 because there is a 6-row subtractive triangle with distinct integers in [1..22] as follows:
%e 1: 6 20 22 3 21 13
%e 2: 14 2 19 18 8
%e 3: 12 17 1 10
%e 4: 5 16 9
%e 5: 11 7
%e 6: 4
%e However, there is no such triangle with distinct integers in [1..21].
%Y Cf. A035312, A035313.
%K nonn,hard,more
%O 1,2
%A _Yi Yang_, Jun 01 2013
%E a(12) from _Yi Yang_, Mar 04 2015
%E a(13) from _Denis Cazor_, Aug 01 2022
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