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 A173237 #24 Mar 04 2024 01:13:34 %S A173237 1,10,2,20,3,30,4,40,5,50,6,60,7,70,8,80,9,90,10,100,11,110,12,120,13, %T A173237 130,14,140,15,150,16,160,17,170,18,180,19,190,20,200,21,210,22,220, %U A173237 23,230,24,240,25,250,26,260,27,270,28,280,29,290,30,300,31,310,32,320,33 %N A173237 Alternate k and 10k for each k. %H A173237 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,2,0,-1). %F A173237 G.f.: x*(1+10*x) / ( (x-1)^2*(1+x)^2 ). - _R. J. Mathar_, Jun 18 2014 %Y A173237 Cf. A008592, A101233. %K A173237 nonn,easy %O A173237 1,2 %A A173237 _Mark Dols_, Feb 13 2010