cp's OEIS Frontend

A385880 Values of u in triples (u, v, w) such that the polynomial x^3 + u*x^2 + v*x + w has 3 distinct negative integer zeros; the triples are ordered by the inequality u < v.

%I A385880 #12 Jul 27 2025 22:38:11
%S A385880 6,7,8,8,9,9,9,10,10,10,10,11,11,11,11,11,12,12,12,12,12,12,12,13,13,
%T A385880 13,13,13,13,13,13,14,14,14,14,14,14,14,14,14,14,15,15,15,15,15,15,15,
%U A385880 15,15,15,15,15,16,16,16,16,16,16,16,16,16,16,16,16,16
%N A385880 Values of u in triples (u, v, w) such that the polynomial x^3 + u*x^2 + v*x + w has 3 distinct negative integer zeros; the triples are ordered by the inequality u < v.
%e A385880 First 20 triples:
%e A385880   u    v    w
%e A385880   6   11    6
%e A385880   7   14    8
%e A385880   8   17   10
%e A385880   8   19   12
%e A385880   9   20   12
%e A385880   9   23   15
%e A385880   9   26   24
%e A385880  10   23   14
%e A385880  10   27   18
%e A385880  10   29   20
%e A385880  10   31   30
%e A385880  11   26   16
%e A385880  11   31   21
%e A385880  11   34   24
%e A385880  11   36   36
%e A385880  11   38   40
%e A385880  12   29   18
%e A385880  12   35   24
%e A385880  12   39   28
%e A385880  12   41   30
%t A385880 z = 140;
%t A385880 t = Table[{b + c + d, c  d + d  b + b  c, b  c  d}, {b, 1, z - 2}, {c, b + 1, z - 1}, {d, c + 1, z}];
%t A385880 t1 = Union[Flatten[t, 2]];
%t A385880 t2 = Take[t1, 20]
%t A385880 Grid[t2]
%Y A385880 Cf. A385779, A386287, A386288.
%K A385880 nonn
%O A385880 1,1
%A A385880 _Clark Kimberling_, Jul 11 2025