%I #18 Jun 20 2017 01:35:18

%S 0,1,4,2,7,3,10,4,13,5,16,6,19,7,22,8,25,9,28,10,31,11,34,12,37,13,40,

%T 14,43,15,46,16,49,17,52,18,55,19,58,20,61,21,64,22,67,23,70,24,73,25,

%U 76,26,79,27,82,28,85,29,88,30,91,31,94,32,97,33,100

%N Central terms of the triangle in A048152.

%C a(n) = A123684(n) for n > 1;

%C a(n) = A048152(2*n-1,n), central terms;

%C also a(n) = A060036(2*n-1,n-1) for n > 1.

%C a(n+1)=the remainder when n^2 is divided by 2n+1. - _J. M. Bergot_, Jun 25 2013

%H Reinhard Zumkeller, <a href="/A225126/b225126.txt">Table of n, a(n) for n = 1..1000</a>

%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,2,0,-1).

%F a(1) = 0, a(2*n) = n and a(2*n+1) = 3*n+1.

%F a(n) = 2*a(n-2)-a(n-4) for n>5. G.f.: -x^2*(x^3-4*x-1) / ((x-1)^2*(x+1)^2). - _Colin Barker_, May 01 2013

%o (Haskell)

%o a225126 n = a048152 (2 * n - 1) n

%o (PARI) a(n)=n--^2%(2*n+1) \\ _Charles R Greathouse IV_, Jun 25 2013

%K nonn,easy

%O 1,3

%A _Reinhard Zumkeller_, Apr 29 2013