cp's OEIS Frontend

A201913 Irregular triangle of possible factorizations of the trinomial x^n + A*x^m + B, where A and B are rational with A*B nonzero and n > m.

%I A201913 #5 Mar 30 2012 17:23:03
%S A201913 1,1,2,1,1,1,1,2,3,1,1,2,2,2,1,3,4,1,2,2,1,1,3,2,3,1,4,5,1,1,1,1,2,1,
%T A201913 1,2,2,2,2,2,1,2,3,3,3,1,1,4,2,4,1,5,6
%N A201913 Irregular triangle of possible factorizations of the trinomial x^n + A*x^m + B, where A and B are rational with A*B nonzero and n > m.
%C A201913 As shown in the example below, for each n, every row sums to n. The rows are a subset of rows in A080576, which lists all partitions of n in graded reflected lexicographic order. Currently, the rows for n=7 are not proved. They are assumed to be {1, 3, 3}, {1, 2, 4}, {3, 4}, {1, 1, 5}, {2, 5}, {1, 6}, {7}.
%H A201913 Andrew Bremner and Maciej Ulas, <a href="http://arxiv.org/abs/1112.4267">On the reducibility type of trinomials</a>, arxiv 1112.4267
%e A201913 The first rows:
%e A201913 1, 1
%e A201913 2
%e A201913 1, 1, 1
%e A201913 1, 2
%e A201913 3
%e A201913 1, 1, 2
%e A201913 2, 2
%e A201913 1, 3
%e A201913 4
%e A201913 1, 2, 2
%e A201913 1, 1, 3
%e A201913 2, 3
%e A201913 1, 4
%e A201913 5
%Y A201913 Cf. A178868 (note that the number A multiplies a linear term only).
%K A201913 nonn,tabf,more
%O A201913 2,3
%A A201913 _T. D. Noe_, Dec 20 2011