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 A047925 #19 Jan 25 2022 21:12:32
%S A047925 8,16,29,37,50,63,71,84,92,105,118,126,139,152,160,173,181,194,207,
%T A047925 215,228,236,249,262,270,283,296,304,317,325,338,351,359,372,385,393,
%U A047925 406,414,427,440,448,461,469,482,495,503,516,529,537,550,558,571,584,592
%N A047925 3rd column of array in A038150.
%H A047925 A. S. Fraenkel, <a href="https://doi.org/10.1016/S0304-3975(00)00062-1">Recent results and questions in combinatorial game complexities</a>, Theoretical Computer Science, vol. 249, no. 2 (2000), 265-288.
%H A047925 A. S. Fraenkel, <a href="https://doi.org/10.1016/S0304-3975(01)00070-6">Arrays, numeration systems and Frankenstein games</a>, Theoret. Comput. Sci. 282 (2002), 271-284; <a href="http://www.wisdom.weizmann.ac.il/~fraenkel/Papers/ans1.ps">preprint</a>.
%t A047925 max = 53; Clear[t]; t[0, 0] = 1; t[n_, 1] := t[n, 1] = 2*t[n, 0] + n + 1; t[n_, 0] := t[n, 0] = For[u = Table[t[m, k], {m, 0, n-1}, {k, 0, max-m}] // Flatten // Union; k = 1, k <= n*(n+1)/2 + 1, k++, If[u[[k]] != k, Return[k]]]; t[n_, k_] := t[n, k] = 3*t[n, k-1] - t[n, k-2]; a[n_] := t[n, 2]; Table[a[n], {n, 0, max}] (* _Jean-François Alcover_, Jul 16 2015 *)
%Y A047925 Cf. A038150.
%K A047925 nonn,nice,easy
%O A047925 0,1
%A A047925 _N. J. A. Sloane_
%E A047925 More terms from _Naohiro Nomoto_, Jun 08 2001