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 A129143 #6 Sep 08 2022 08:45:30 %S A129143 1,2,3,4,5,6,8,9,10,11,16,17,18,19,20,32,33,34,35,36,37,64,65,66,67, %T A129143 68,69,70,128,129,130,131,132,133,134,135,256,257,258,259,260,261,262, %U A129143 263,264,512,513,514,515,516,517,518,519,520,521,1024,1025,1026,1027,1028 %N A129143 Start with the empty sequence and append in step k the consecutive numbers 2^(k-1) to 2^(k-1)+k-1. %C A129143 Inspired by A127330. %H A129143 Ivan Neretin, <a href="/A129143/b129143.txt">Table of n, a(n) for n = 1..5151</a> %e A129143 In step 5 the numbers 2^4 to 2^4+4 are appended: 16, 17, 18, 19, 20. %t A129143 Table[2^n + k, {n, 0, 10}, {k, 0, n}] // Flatten (* _Ivan Neretin_, Aug 30 2015 *) %o A129143 (Magma) &cat[ [2^k..2^k+k]: k in [0..11] ]; %Y A129143 Cf. A127330, A129142. %K A129143 nonn,easy %O A129143 1,2 %A A129143 _Klaus Brockhaus_, Mar 31 2007