%I A147678
%S A147678 1,2,2,4,5,10,12,24,27,54,58,116,121,242,248,496,503,1006,1014,2028,
%T A147678 2037,4074,4084,8168,8179,16358,16370,32740,32753,65506,65520,131040,
%U A147678 131055,262110,262126,524252,524269,1048538,1048556,2097112,2097131
%N A147678 Double, add 0, double, add 1, double, add 2, double, add 3, etc.
%C A147678 A147675-A147678 are from a quiz that someone asked me to help them with.
%F A147678 a(n)=4*a(n-2)-5*a(n-4)+2*a(n-6). G.f.: -x*(2*x+1)*(2*x^4-2*x^2+1)/((2*x^2-1)*(x-1)^2*(1+x)^2). 
               a(n)=(1+(-1)^n)/2+2*A016116(n)-A105811(n+3)/4-3*(n+1)/4. [From R. 
               J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 22 2009]
%F A147678 a(n) = 2*a(n-1) - (n mod 2)*(a(n-1) - (n-3)/2). [From Reinhard Zumkeller 
               (reinhard.zumkeller(AT)gmail.com), Apr 22 2009]
%Y A147678 Sequence in context: A135586 A116646 A091188 this_sequence A127712 A032090 
               A000014
%Y A147678 Adjacent sequences: A147675 A147676 A147677 this_sequence A147679 A147680 
               A147681
%K A147678 nonn
%O A147678 1,2
%A A147678 N. J. A. Sloane (njas(AT)research.att.com), Apr 21 2009
%E A147678 More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 22 2009