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 A106450 #11 Apr 19 2016 21:27:40 %S A106450 2,3,0,1,3,7,2,5,5,11,4,9,7,15,6,13,9,19,8,17,11,23,10,21,13,27,12,25, %T A106450 15,31,14,29,17,35,16,33,19,39,18,37,21,43,20,41,23,47,22,45,25,51,24, %U A106450 49,27,55,26,53,29,59,28,57,31,63,30,61,33,67,32,65,35,71,34,69,37,75 %N A106450 a(n) = A004443(n) if n is odd, a(n) = A004443(n)/2 if n is even. %H A106450 Colin Barker, <a href="/A106450/b106450.txt">Table of n, a(n) for n = 0..1000</a> %H A106450 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (0,1,0,1,0,-1). %F A106450 a(4*n+1) = 4*n+3, a(4*n+2) = 2*n, a(4*n+3) = 4*n+1, a(4*n+4) = 2*n+3. %F A106450 From _Colin Barker_, Apr 19 2016: (Start) %F A106450 a(n) = ((2+4*i)*(-i)^n+(2-4*i)*i^n-(-3+(-1)^n)*n)/4 for n>0 where i is the imaginary unit. %F A106450 a(n) = a(n-2)+a(n-4)-a(n-6) for n>6. %F A106450 G.f.: (2+3*x-2*x^2-2*x^3+x^4+3*x^5+x^6) / ((1-x)^2*(1+x)^2*(1+x^2)). %F A106450 (End) %F A106450 From _Ilya Gutkovskiy_, Apr 19 2016: (Start) %F A106450 a(n) = (4*floor(1/(n+1)) - (-1)^n*n + 3*n + 8*sin((Pi*n)/2) + 4*cos((Pi*n)/2))/4. %F A106450 E.g.f.: 1 + cos(x) + x*cosh(x) + 2*sin(x) + x*sinh(x)/2. (End) %o A106450 (PARI) Vec((2+3*x-2*x^2-2*x^3+x^4+3*x^5+x^6)/((1-x)^2*(1+x)^2*(1+x^2)) + O(x^50)) \\ _Colin Barker_, Apr 19 2016 %Y A106450 Skipping the initial term (a(0)=2), this is row 2 of A106449. %K A106450 nonn,easy %O A106450 0,1 %A A106450 _Antti Karttunen_, May 21 2005