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 A169943 #14 Oct 10 2017 15:33:03
%S A169943 1,0,3,4,7,8,21,20,53,56,89,112,197,220,397,456,711,850,1347,1428,
%T A169943 2303,2642,3777,4636,6693,7550,11109,12876,17965,21000,29207,32952,
%U A169943 46263,53372,71069,82660,111877,126042,172461,195898,256577
%N A169943 Second entry in row n of triangle in A169940.
%C A169943 Wanted: a recurrence. Are any of A169940-A169954 related to any other entries in the OEIS?
%H A169943 <a href="/index/Ca#CARRYLESS">Index entries for sequences related to carryless arithmetic</a>
%F A169943 a(n) = A169953(n) - A169953(n-1) for n>2.
%t A169943 (* Very slow *) a[n_] := Module[{dd, xx, mm}, dd = Join[{1}, PadLeft[ IntegerDigits[#, 2], n - 1], {1}] & /@ Range[0, 2^(n - 1) - 1]; xx = (((x^Range[n, 0, -1]).#) & /@ dd)^2 // Expand; mm = Max[ CoefficientList[ #, x]] & /@ xx; Count[mm, 3]]; Table[an = a[n]; Print["a(", n, ") = ", an]; an, {n, 2, 20}] (* _Jean-François Alcover_, Oct 10 2017 *)
%Y A169943 Related to thickness: A169940-A169954, A061909.
%K A169943 nonn
%O A169943 2,3
%A A169943 _N. J. A. Sloane_, Aug 01 2010
%E A169943 a(15)-a(30) from _Nathaniel Johnston_, Nov 12 2010
%E A169943 a(31)-a(42) from _Andrew Howroyd_, Jul 09 2017