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 A029746 #22 Jul 08 2025 19:18:55
%S A029746 1,2,4,7,8,14,16,28,32,56,64,112,128,224,256,448,512,896,1024,1792,
%T A029746 2048,3584,4096,7168,8192,14336,16384,28672,32768,57344,65536,114688,
%U A029746 131072,229376,262144,458752,524288,917504,1048576,1835008,2097152
%N A029746 Numbers of the form 2^k or 7*2^k.
%H A029746 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (0,2).
%F A029746 G.f.: (1+2x+2x^2+3x^3)/(1-2x^2). - _Michael Somos_, Nov 05 2002
%F A029746 Sum_{n>=0} 1/a(n) = 16/7. - _Amiram Eldar_, Jan 17 2022
%t A029746 Sort[Flatten[{#,7#}&/@(2^Range[0,21])]] (* or *) CoefficientList[Series[ (1+2x+2x^2+3x^3)/(1-2x^2),{x,0,50}],x] (* _Harvey P. Dale_, Apr 23 2011 *)
%o A029746 (PARI) a(n)=if(n<0,0,if(n<2,2^n,if(n%2,7/2,2)*2^(n\2)))
%Y A029746 Cf. A000079, A005009, A029744, A029748.
%K A029746 nonn
%O A029746 0,2
%A A029746 _N. J. A. Sloane_