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%I #28 Jan 14 2024 11:53:42
%S 12,28,44,60,76,92,108,124,140,156,172,188,204,220,236,252,268,284,
%T 300,316,332,348,364,380,396,412,428,444,460,476,492,508,524,540,556,
%U 572,588,604,620,636,652,668,684,700,716,732,748,764,780,796,812,828,844
%N a(n) = 16*n - 4.
%C For n > 3, the number of squares on the infinite 4-column chessboard at <= n knight moves from any fixed start point.
%H Vincenzo Librandi, <a href="/A098502/b098502.txt">Table of n, a(n) for n = 1..5000</a>
%H Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/RecursiveSequences.html">Recursive Sequences</a>
%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1).
%H <a href="/index/Se#sequences_which_agree_for_a_long_time">Index entries for sequences which agree for a long time but are different</a>
%e G.f.: 4*x*(3+x)/(1-x)^2. - _Colin Barker_, Jan 09 2012
%t Range[12, 1000, 16] (* _Vladimir Joseph Stephan Orlovsky_, May 31 2011 *)
%o (Magma) [16*n - 4: n in [1..60]]; // _Vincenzo Librandi_, Jul 24 2011
%o (PARI) a(n)=16*n-4 \\ _Charles R Greathouse IV_, Jul 10 2016
%Y Cf. A008590, A017629, A098498, A158953.
%K nonn,easy
%O 1,1
%A _Ralf Stephan_, Sep 15 2004
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