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 A187839 #12 Feb 12 2018 08:53:12 %S A187839 1,3,4,7,8,9,12,14,15,17,19,21,22,24,26,28,30,31,33,35,37,38,41,42,44, %T A187839 46,47,50,51,52,55,56,58,60,62,63,65,68,69,71,73,74,76,78,80,82,83,85, %U A187839 86,89,90,92,94,96,98,99,101,103,104,107,108,111,112,114,116,117,119,121,123,124,126,128,130,132,134,135,137,139,140,142,144,146 %N A187839 Rank transform of the sequence floor(n*sqrt(2)-1/2); complement of A187840. %C A187839 See A187224. %H A187839 G. C. Greubel, <a href="/A187839/b187839.txt">Table of n, a(n) for n = 1..10000</a> %t A187839 r=2^(1/2); %t A187839 seqA = Table[Floor[r*n-1/2], {n, 1, 220}] %t A187839 seqB = Table[n, {n, 1, 220}]; (* A000027 *) %t A187839 jointRank[{seqA_, %t A187839 seqB_}] := {Flatten@Position[#1, {_, 1}], %t A187839 Flatten@Position[#1, {_, 2}]} &[ %t A187839 Sort@Flatten[{{#1, 1} & /@ seqA, {#1, 2} & /@ seqB}, 1]]; %t A187839 limseqU = %t A187839 FixedPoint[jointRank[{seqA, #1[[1]]}] &, %t A187839 jointRank[{seqA, seqB}]][[1]] (* A187839 *) %t A187839 Complement[Range[Length[seqA]], limseqU] (* A187840 *) %t A187839 (* _Peter J. C. Moses_, Mar 13 2011 *) %Y A187839 Cf. A187224, A187840. %K A187839 nonn %O A187839 1,2 %A A187839 _Clark Kimberling_, Mar 13 2011