cp's OEIS Frontend

A331425 Divide each side of a triangle into 2*n (n>=1) equal parts and trace the corresponding cevians, i.e., join every point, except for the first and last ones, with the opposite vertex. a(n) is the number of points at which three cevians meet.

%I A331425 #16 Feb 14 2020 18:42:58
%S A331425 1,7,13,19,25,31,37,43,49,61,61,91,73,79,91,91,97,103,109,133,133,127,
%T A331425 133,187,145,151,157,175,169,235,181,187,205,199,229,283,217,223,235,
%U A331425 325,241,283,253,271,331,271,277,343,289,301,301,319,313,319,349,439
%N A331425 Divide each side of a triangle into 2*n (n>=1) equal parts and trace the corresponding cevians, i.e., join every point, except for the first and last ones, with the opposite vertex. a(n) is the number of points at which three cevians meet.
%C A331425 A bisection of A331423.
%F A331425 a(n) = A331423(2*n).
%t A331425 CevIntersections[n_] := Length[Solve[(n - i)*(n - j)*(n - k) - i*j*k == 0 && 0 < i < n &&  0 < j < n && 0 < k < n, {i, j, k}, Integers]];
%t A331425 Map[CevIntersections[#] &, Range[2,50,2]]
%Y A331425 Cf. A331423, A331428.
%K A331425 nonn
%O A331425 1,2
%A A331425 _César Eliud Lozada_, Jan 16 2020