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 A355339 #10 Jun 29 2022 10:31:57
%S A355339 0,3,1,3,3,7,1,3,5,3,5,11,3,11,1,3,5,7,7,3,5,7,9,19,7,3,5,19,3,11,1,3,
%T A355339 5,7,9,11,13,11,7,3,5,7,9,11,13,15,17,35,15,11,7,3,5,7,9,35,7,3,5,19,
%U A355339 3,11,1,3,5,7,9,11,13,15,17,19,21,23,23,19,15
%N A355339 a(n) is the number of central even terms in the n-th row of triangle A355320; a(0) = 0.
%H A355339 Rémy Sigrist, <a href="/A355339/b355339.txt">Table of n, a(n) for n = 0..8192</a>
%F A355339 Conjecture: a(n) = 1 iff n > 0 and n belongs to A000918.
%e A355339 The first terms, alongside the corresponding rows of A355320, are:
%e A355339 n a(n) n-th row of A355320
%e A355339 - ---- -------------------------------------------------------------
%e A355339 0 0 1
%e A355339 1 3 1 (0 0 0) 1
%e A355339 2 1 1 0 0 1 (2) 1 0 0 1
%e A355339 3 3 1 0 0 2 3 (2 0 2) 3 2 0 0 1
%e A355339 4 3 1 0 0 3 4 3 1 (6 8 6) 1 3 4 3 0 0 1
%e A355339 5 7 1 0 0 4 5 4 3(12 16 12 6 12 16 12) 3 4 5 4 0 0 1
%o A355339 (PARI) { rr = 0; r = 1; for (n=0, 76, print1 (max(0, 2*valuation(r >> (2*n), 2)-1)", "); [rr, r] = [r, bitxor(bitxor(r, r<<4), bitxor(rr<<3, rr<<5))]) }
%Y A355339 Cf. A000918, A355320.
%K A355339 nonn
%O A355339 0,2
%A A355339 _Rémy Sigrist_, Jun 29 2022