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 A031884 #24 Jul 21 2025 14:39:27
%S A031884 1,3,15,79,141,51,787,495,171,937,903,745,2851,1611,1057,3811,5769,
%T A031884 4893,8719,10683,9841,24073,9567,28245,25687,3507,26943,35743,44805,
%U A031884 51979,64723,23205,50779,51475,264075,155833,238057,178755,143311,400591,223095,181581,466813
%N A031884 Smaller of a pair of consecutive lucky numbers with a gap of 2n.
%C A031884 a(n) is the first occurrence of a difference of 2n between A000959(k+1) and A000959(k). - _Robert G. Wilson v_, May 12 2006
%C A031884 a(136) > 10^9. - _Donovan Johnson_, Dec 07 2011
%C A031884 Unknown terms a(166), a(176), a(178), a(182), and a(185) through a(209) are all greater than 10^10. - _Kevin P. Thompson_, Nov 24 2021
%H A031884 Kevin P. Thompson, <a href="/A031884/b031884.txt">Table of n, a(n) for n = 1..165</a> (terms 1..135 from Donovan Johnson)
%H A031884 Kevin P. Thompson, <a href="/A031884/a031884.txt">Table of n, a(n) for n = 1..210</a> with unknown terms
%e A031884 a(4) = 79 since the lucky numbers A000959(20) = 79 and A000959(21) = 87 are the first consecutive pair with difference 2*4 = 8.
%t A031884 lst = Range[1, 10^6, 2]; i = 2; While[ i <= (len = Length@lst) && (k = lst[[i]]) <= len, lst = Drop[lst, {k, len, k}]; i++ ]; f[n_] := Block[{k = 1}, While[t[[k + 1]] - t[[k]] != 2n, k++ ]; t[[k]]]; Array[f, 41] (* _Robert G. Wilson v_, May 12 2006 *)
%Y A031884 Cf. A000959, A031885, A031883, A031158, A031886, A031888, A031890, A031892, A031894, A031896, A031898, A031900, A031902.
%K A031884 nonn
%O A031884 1,2
%A A031884 _Patrick De Geest_
%E A031884 More terms from _Robert G. Wilson v_, May 12 2006