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A081348 First row in maze arrangement of natural numbers. 5

%I

%S 1,6,7,20,21,42,43,72,73,110,111,156,157,210,211,272,273,342,343,420,

%T 421,506,507,600,601,702,703,812,813,930,931,1056,1057,1190,1191,1332,

%U 1333,1482,1483,1640,1641,1806,1807,1980,1981,2162,2163,2352,2353,2550

%N First row in maze arrangement of natural numbers.

%H Vincenzo Librandi, <a href="/A081348/b081348.txt">Table of n, a(n) for n = 0..1000</a>

%H <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (1,2,-2,-1,1).

%F a(n) = (2*n^2+4*n+3-(2*n+1)(-1)^n)/2.

%F a(2*n) = A054569(n).

%F a(2*n+1) = 2*A014105(n+1).

%F G.f.: (1+5*x-x^2+3*x^3)/((1-x)^3*(1+x)^2). - _Colin Barker_, Apr 17 2012

%t 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 (MAGMA) [(2*n^2+4*n+3-(2*n+1)*(-1)^n)/2: n in [0..50]]; // _Vincenzo Librandi_, Aug 08 2013

%Y Cf. A081347, A080335.

%K easy,nonn

%O 0,2

%A _Paul Barry_, Mar 19 2003

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Last modified August 18 15:00 EDT 2019. Contains 326106 sequences. (Running on oeis4.)