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 A061880 #3 Jun 21 2014 07:57:21
%S A061880 209,308,319,407,418,429,506,517,528,539,605,616,627,638,649,704,715,
%T A061880 726,737,748,759,803,814,825,836,847,858,869,902,913,924,935,946,957,
%U A061880 968,979,2090,3080,3091,3190,4070,4081,4092,4180,4191,4290,5060,5071
%N A061880 First (leftmost) digit - second digit + third digit - fourth digit .... = 11.
%C A061880 Note that all entries are divisible by eleven.
%H A061880 Harvey P. Dale, <a href="/A061880/b061880.txt">Table of n, a(n) for n = 1..1000</a>
%t A061880 Select[Range[11,6000,11],Total[Times@@@Partition[Riffle[ IntegerDigits[ #],{1,-1},{2,-1,2}],2]]==11&] (* _Harvey P. Dale_, Jun 21 2014 *)
%Y A061880 Cf. A008593, A060978-A060980, A060982, A061470-A061479, A061870-A061882.
%K A061880 base,nonn,easy
%O A061880 1,1
%A A061880 Larry Reeves (larryr(AT)acm.org), May 15 2001