%N Refactorable numbers that are the sum of two refactorable numbers in exactly one way.
%C Sequence is a result of investigation on the marked region in graph of A172398(A033950(n)) that is in Links section. Also there are other sequences that marked region has.
%H Altug Alkan, <a href="/A282519/a282519.png">Illustration of A172398(A033950(n))</a>
%H S. Colton, <a href="https://cs.uwaterloo.ca/journals/JIS/colton/joisol.html">Refactorable Numbers - A Machine Invention</a>, J. Integer Sequences, Vol. 2, 1999.
%H Joshua Zelinsky, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL5/Zelinsky/zelinsky9.html">Tau Numbers: A Partial Proof of a Conjecture and Other Results </a>, Journal of Integer Sequences, Vol. 5 (2002), Article 02.2.8
%e Refactorable number 1500625 is a term because 1500625 is the sum of two refactorable numbers in exactly one way, that is, 1500625 = 5^4 * 7^4 = 3^2 * 131^2 + 2^7 * 13 * 809.
%Y Cf. A033950, A172398, A280634, A281663.
%A _Altug Alkan_, Feb 17 2017
%E a(10) from _Giovanni Resta_, Feb 17 2017