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 A184426 #8 Mar 30 2012 18:57:13 %S A184426 2,6,10,15,22,29,37,47,57,68,80,94,108,123,139,156,174,194,214,235, %T A184426 257,280,304,330,356,383,411,440,470,501,534,567,601,636,672,709,747, %U A184426 786,826,868,910,953,997,1042,1088,1135,1183,1232,1283,1334,1386,1439,1493,1548,1604,1661,1719,1778,1839,1900,1962,2025,2089,2154,2220,2287,2355,2424,2494,2566,2638,2711,2785,2860,2936,3013,3091,3170,3250,3331,3413,3496,3581,3666 %N A184426 Upper s-Wythoff sequence, where s=A000217 (triangular numbers). Complement of A184425. %C A184426 See A184117 for the definition of lower and upper s-Wythoff sequences. %t A184426 mex:=First[Complement[Range[1,Max[#1]+1],#1]]&; %t A184426 s[n_]:=n (n+1)/2;a[1]=1;b[n_]:=b[n]=s[n]+a[n]; %t A184426 a[n_]:=a[n]=mex[Flatten[Table[{a[i],b[i]},{i,1,n-1}]]]; %t A184426 Table[s[n],{n,40}] %t A184426 Table[a[n],{n,120}] %t A184426 Table[b[n],{n,100}] %Y A184426 Cf. A184117, A184425. %K A184426 nonn %O A184426 1,1 %A A184426 _Clark Kimberling_, Jan 14 2011