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 A152135 #19 Apr 20 2023 04:23:43
%S A152135 12,36,74,134,216,328,470,650,868,1132,1442,1806,2224,2704,3246,3858,
%T A152135 4540,5300,6138,7062,8072,9176,10374,11674,13076,14588,16210,17950,
%U A152135 19808,21792,23902,26146,28524,31044,33706,36518,39480,42600,45878
%N A152135 Maximal length of rook tour on an n X n+4 board.
%D A152135 M. Gardner, Knotted Doughnuts and Other Mathematical Entertainments. Freeman, NY, 1986, p. 76.
%H A152135 Vincenzo Librandi, <a href="/A152135/b152135.txt">Table of n, a(n) for n = 1..1000</a>
%H A152135 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (3,-2,-2,3,-1).
%F A152135 G.f.: -2*x*(-6+5*x^2-4*x^3+x^4)/(1+x)/(x-1)^4.
%F A152135 From _R. J. Mathar_, May 13 2010: (Start)
%F A152135 a(n) = +3*a(n-1) -2*a(n-2) -2*a(n-3) +3*a(n-4) -a(n-5).
%F A152135 a(n) = 19*n/3+3/2+2*n^3/3+4*n^2+(-1)^n/2. (End)
%t A152135 LinearRecurrence[{3, -2, -2, 3, -1}, {12, 36, 74, 134, 216}, 40] (* _Vincenzo Librandi_, Dec 11 2012 *)
%o A152135 (Magma) I:=[12, 36, 74, 134, 216]; [n le 5 select I[n] else 3*Self(n-1)-2*Self(n-2)-2*Self(n-3)+3*Self(n-4)-Self(n-5): n in [1..40]]; // _Vincenzo Librandi_, Dec 11 2012
%Y A152135 Cf. A006071, A152132, A152133, A152134.
%K A152135 nonn,easy
%O A152135 1,1
%A A152135 _R. J. Mathar_, Mar 22 2009