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 A254100 #23 Apr 08 2018 20:08:42
%S A254100 4,9,19,31,55,73,101,145,167,205,253,293,317,355,413,473,521,569,623,
%T A254100 677,737,763,833,917,983,1027,1051,1121,1171,1273,1337,1411,1471,1571,
%U A254100 1619,1663,1681,1807,1957,1991,2087,2113,2171,2245,2275,2335,2401,2497,2593,2713,2771,2831,2977,3047,3113
%N A254100 Postludic numbers: Second column of Ludic array A255127.
%H A254100 Antti Karttunen, <a href="/A254100/b254100.txt">Table of n, a(n) for n = 1..10001</a>
%F A254100 a(n) = A255407(A001248(n)).
%t A254100 rows = 100; cols = 2; t = Range[2, 10^4]; r = {1}; n = 1; While[n <= rows, k = First[t]; AppendTo[r, k]; t0 = t; t = Drop[t, {1, -1, k}]; ro[n++] = Complement[t0, t][[1 ;; cols]]]; A = Array[ro, rows]; Table[A[[n, 2]], {n, 1, rows} ] (* _Jean-François Alcover_, Mar 14 2016, after _Ray Chandler_ *)
%o A254100 (Scheme) (define (A254100 n) (A255127bi n 2)) ;; A255127bi given in A255127.
%Y A254100 Column 2 of A255127. (Row 2 of A255129). Positions of 2's in A260739.
%Y A254100 Subsequence of A192607, A302036 and A302038.
%Y A254100 Cf. A276576, A276606 (first differences).
%Y A254100 Cf. also A001248, A219178.
%K A254100 nonn
%O A254100 1,1
%A A254100 _Antti Karttunen_, Feb 22 2015