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 A355050 #6 Jul 26 2022 13:57:20
%S A355050 3,10,46,215,1221,6384,31153,140320,596779,2416833,9417531,35541184,
%T A355050 130684964,470159267,1660756778,5775367751,19816896743,67213026352,
%U A355050 225673938496,751028439756,2479882044054,8131813096411
%N A355050 Number of achiral orthoplex n-ominoes with cell centers determining n-3 space.
%C A355050 Orthoplex polyominoes are connected sets of cells of regular tilings with Schläfli symbols {}, {4}, {3,4}, {3,3,4}, {3,3,3,4}, etc. These are tilings of regular orthoplexes projected on their circumspheres. Orthoplex polyominoes are equivalent to multidimensional polyominoes that do not extend more than two units along any axis, i.e., fit within a 2^d cube. This sequence is obtained using the first formula below. An achiral polyomino is identical to its reflection.
%F A355050 a(n) = A355048(n) - A355049(n) = 2*A355048(n) - A355047(n) = A355047(n) - 2*A355049(n).
%e A355050 a(6)=3 because there are 3 hexominoes in 2^3 space, all achiral. The two vacant cells share just a face, an edge, or a vertex.
%Y A355050 Cf. A355047 (oriented), A355048 (unoriented), A355049 (chiral), A355051 (asymmetric), A355055 (multidimensional).
%K A355050 nonn,easy
%O A355050 6,1
%A A355050 _Robert A. Russell_, Jun 16 2022