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 A231331 #8 Sep 23 2023 08:52:26 %S A231331 1,1,2,3,6,10,20,35,74,130,258,473,1007,1830,3912,7093,15233,27831, %T A231331 60458,109555,239039,433654,946849,1709524,3746021,6750928 %N A231331 Number of distinct terms in row n of triangle A230871. %C A231331 Length of row n in triangle A231330. %o A231331 (Haskell) %o A231331 a231331 = length . a231330_row %o A231331 (PARI) vf(v) = #Set(v); %o A231331 lista(nn) = my(va=[0], vb=[1]); print1(vf(va), ", "); print1(vf(vb), ", "); for (n=2, nn, v = vector(2^(n-1), k, j=(k+1)\2; i=(j+1)\2; y=vb[j]; x=va[i]; if (k%2, y+x, 3*y-x)); print1(vf(v), ", "); va = vb; vb = v;); \\ _Michel Marcus_, Sep 23 2023 %Y A231331 Cf. A231335. %K A231331 nonn,more %O A231331 0,3 %A A231331 _Reinhard Zumkeller_, Nov 07 2013 %E A231331 a(23)-a(25) from _Michel Marcus_, Sep 23 2023