%I #37 Dec 17 2018 18:41:03
%S 39,24,21,15,18,24,189,67734
%N a(n) is the smallest magic sum of any 3 X 3 magic square which contains exactly n triangular numbers.
%H Andrew Bremner, <a href="http://www.multimagie.com/Bremner2.pdf">On squares of squares II</a>, Acta Arithmetica 99 (2001), pp. 289-308.
%H Multimagic Squares, <a href="http://www.multimagie.com/English/SmallestTriangularExpanded.htm#Unsolved1Order3">An unsolved problem</a>
%H The Prime Puzzles and Problems Connection, <a href="http://www.primepuzzles.net/problems/prob_063.htm">Problem 63</a>
%H The Prime Puzzles and Problems Connection, <a href="http://www.primepuzzles.net/puzzles/puzz_079.htm">Puzzle 79</a>
%H Arkadiusz Wesolowski, <a href="/A268854/a268854.txt">Examples of these magic squares</a>
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Magic_square">Magic square</a>
%H <a href="/index/Mag#magic">Index entries for sequences related to magic squares</a>
%Y Cf. A221669, A268855, A268856, A269231, A271020.
%K nonn,fini,hard,more
%O 0,1
%A _Arkadiusz Wesolowski_, Feb 14 2016