This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A324039 #10 Oct 20 2022 16:26:38 %S A324039 1,1,2,2,4,8,11,19,31,50,88,146,241,407,675,1118,1871,3102,5175,8633, %T A324039 14394,23999,40002,66666,111044,185192,308442,514138,857283,1428537, %U A324039 2381021 %N A324039 Row lengths of the irregular triangles A324038 and A324246. %F A324039 a(n) = 2*a(n-1) - a_1(n-1), for n >= 2, and a(0) = 1 = a(1), where a_1(k) is the number of entries 1 (mod 3) in row k of A324246 given in A324040(k). %e A324039 a(5) = 8 = 2*a(4) because a_1(4) = A324040(4) = 0. %e A324039 a(6) = 2*a(5) - 5 = 16 - 5 = 11 because a_1(5) = A324040(5) = 5. %Y A324039 Cf. A324038, A324040, A324246. %K A324039 nonn,easy %O A324039 0,3 %A A324039 _Nicolas Vaillant_, Philippe Delarue, _Wolfdieter Lang_, May 09 2019