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 A334930 #20 Jul 03 2020 23:34:05
%S A334930 1,11,13,91,109,731,877,5851,7021,46811,56173,374491,449389,2995931,
%T A334930 3595117,23967451,28760941,191739611,230087533,1533916891,1840700269,
%U A334930 12271335131,14725602157,98170681051,117804817261,785365448411,942438538093,6282923587291,7539508304749
%N A334930 Numbers that generate rotationally symmetrical XOR-triangles featuring singleton zero bits in a hexagonal arrangement.
%C A334930 Subset of A334556.
%C A334930 No zero appears in the center of the figure, thus a(n) does not intersect A334769.
%C A334930 Numbers m with A070939(m) (mod 3) = 1 involving alternating run lengths of a singleton zero separated by a pair of 1s in the binary expansion, admitting an initial or final singleton 1.
%H A334930 Michael De Vlieger, <a href="/A334930/b334930.txt">Table of n, a(n) for n = 1..2215</a>
%H A334930 Michael De Vlieger, <a href="/A334930/a334930.png">Diagram montage</a> of XOR-triangles resulting from a(n) with 2 <= n <= 33.
%H A334930 Michael De Vlieger, <a href="http://vincico.com/seq/a334769.html">Central zero-triangles in rotationally symmetrical XOR-Triangles</a>, 2020.
%H A334930 <a href="/index/Bi#binary">Index entries for sequences related to binary expansion of n</a>
%H A334930 <a href="/index/X#XOR-triangles">Index entries for sequences related to XOR-triangles</a>
%F A334930 G.f.: (1 + 11*x + 4*x^2 - 8*x^3)/(1 - 9*x^2 + 8*x^4).
%F A334930 a(n) = - (4/7) - (1/7)*(-1)^(n-1) + ((6 + 10*sqrt(2))/7)*(2*sqrt(2))^(n-1) + ((6 - 10*sqrt(2))/7)*(-2*sqrt(2))^(n-1) - _Alejandro J. Becerra Jr._, May 31 2020
%e A334930 Diagrams of a(2)-a(5), replacing “0” with “.” and “1” with “@” for clarity:
%e A334930 a(2)=11 a(3)=13
%e A334930 @ . @ @ @ @ . @
%e A334930 @ @ . . @ @
%e A334930 . @ @ .
%e A334930 @ @
%e A334930 .
%e A334930 a(4) = 91 a(5) = 109
%e A334930 @ . @ @ . @ @ @ @ . @ @ . @
%e A334930 @ @ . @ @ . . @ @ . @ @
%e A334930 . @ @ . @ @ . @ @ .
%e A334930 @ . @ @ @ @ . @
%e A334930 @ @ . . @ @
%e A334930 . @ @ .
%e A334930 @ @
%t A334930 CoefficientList[Series[(1 + 11 x + 4 x^2 - 8 x^3)/(1 - 9 x^2 + 8 x^4), {x, 0, 28}], x]
%t A334930 (* Generate a textual plot of XOR-triangle T(n) *)
%t A334930 xortri[n_Integer] := TableForm@ MapIndexed[StringJoin[ConstantArray[" ", First@ #2 - 1], StringJoin @@ Riffle[Map[If[# == 0, "." (*0*), "@" (*1*)] &, #1], " "]] &, NestWhileList[Map[BitXor @@ # &, Partition[#, 2, 1]] &, IntegerDigits[n, 2], Length@ # > 1 &]]
%Y A334930 Cf. A334556, A334769, A334931, A334932.
%K A334930 nonn,easy
%O A334930 1,2
%A A334930 _Michael De Vlieger_, May 16 2020