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 A181557 #5 Nov 19 2019 03:35:06 %S A181557 1,3,5,9,13,16,18,27,29,35,38,46,49,53,59,69,75,80,83,87,90,95,100, %T A181557 102,106,117,120,136,138,141,143,149,151,154,156,159,164,167,178,182, %U A181557 185,187,201,205,211,215,217,221,227,229,232,246,248,256,265,271,283,286 %N A181557 Indices k for which A031883(k) = 2 = A000959(k+1)-A000959(k), i.e., indices of (lesser) "twin" lucky numbers. %H A181557 Amiram Eldar, <a href="/A181557/b181557.txt">Table of n, a(n) for n = 1..10000</a> %Y A181557 Cf. A000959, A031883. %K A181557 nonn %O A181557 1,2 %A A181557 _M. F. Hasler_, Oct 31 2010