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 A081348 #13 Sep 08 2022 08:45:09
%S A081348 1,6,7,20,21,42,43,72,73,110,111,156,157,210,211,272,273,342,343,420,
%T A081348 421,506,507,600,601,702,703,812,813,930,931,1056,1057,1190,1191,1332,
%U A081348 1333,1482,1483,1640,1641,1806,1807,1980,1981,2162,2163,2352,2353,2550
%N A081348 First row in maze arrangement of natural numbers.
%H A081348 Vincenzo Librandi, <a href="/A081348/b081348.txt">Table of n, a(n) for n = 0..1000</a>
%H A081348 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (1,2,-2,-1,1).
%F A081348 a(n) = (2*n^2+4*n+3-(2*n+1)(-1)^n)/2.
%F A081348 a(2*n) = A054569(n).
%F A081348 a(2*n+1) = 2*A014105(n+1).
%F A081348 G.f.: (1+5*x-x^2+3*x^3)/((1-x)^3*(1+x)^2). - _Colin Barker_, Apr 17 2012
%t A081348 CoefficientList[Series[(1 + 5 x - x^2 + 3 x^3) / ((1 - x)^3 (1 + x)^2), {x, 0, 60}], x] (* _Vincenzo Librandi_, Aug 08 2013 *)
%o A081348 (Magma) [(2*n^2+4*n+3-(2*n+1)*(-1)^n)/2: n in [0..50]]; // _Vincenzo Librandi_, Aug 08 2013
%Y A081348 Cf. A081347, A080335.
%K A081348 easy,nonn
%O A081348 0,2
%A A081348 _Paul Barry_, Mar 19 2003