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 A173870 #5 Feb 20 2019 09:56:19 %S A173870 6,14,20,22,30,38,46,62,70,72,78,84,86,94,126,134,142,148,150,158,174, %T A173870 190,254,262,270,272,276,278,286,294,302,318,340,342,350,382,510,518, %U A173870 526,532,534,542,550,558,574,584,590,596,598,606,638,686,702,766,1022 %N A173870 Consider each term k contained in A114994; write 2k if and only if 2k is not a member of A114994. %C A173870 Recall that A114994 can be regarded as a table with row lengths A000041(n). %C A173870 Likewise, a(n) has row lengths 0,1,1,3,3,7,8,14,18,28,35,53,67,... which appears to coincide with sequence A117989. %C A173870 The row lengths also match 1 2 3 5 7 11 15 22 ... minus 1 1 2 2 4 4 7 8 ... - _Alford Arnold_, Mar 30 2010 %e A173870 Row three of A114994 is 4,5,7 when doubled becomes 8,10,14. %e A173870 8 and 10 are in A114994 so not in a(n); 14 is not in A114994 so is in a(n). %Y A173870 Cf. A000041 A114994 A117989 (A125106, A126441, A161924)(3 closely related sequences). %Y A173870 Cf. A002865 [From _Alford Arnold_, Mar 30 2010] %K A173870 nonn,tabf %O A173870 0,1 %A A173870 _Alford Arnold_, Mar 01 2010