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 A245179 #23 Sep 08 2022 08:46:08
%S A245179 7,11,13,19,25,35,49,67,97,131,193,259,385,515,769,1027,1537,2051,
%T A245179 3073,4099,6145,8195,12289,16387,24577,32771,49153,65539,98305,131075,
%U A245179 196609,262147,393217,524291,786433,1048579,1572865,2097155,3145729,4194307,6291457
%N A245179 Numbers of the form 2^k+3 or 3*2^k+1, k >= 2.
%C A245179 Numbers whose binary expansion is 10..011 or 110..01.
%H A245179 Vincenzo Librandi, <a href="/A245179/b245179.txt">Table of n, a(n) for n = 1..1000</a>
%H A245179 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,3,0,-2).
%F A245179 a(2k) = 2^(k+2)+3, a(2k+1) = 3*2^(k+1)+1. - _N. J. A. Sloane_, Jul 19 2014
%F A245179 a(n) = 3*a(n-2)-2*a(n-4). G.f.: -x*(14*x^3+8*x^2-11*x-7) / ((x-1)*(x+1)*(2*x^2-1)). - _Colin Barker_, Jul 19 2014
%t A245179 CoefficientList[Series[- (14 x^3 + 8 x^2 - 11 x - 7)/((x - 1) (x + 1) (2 x^2 - 1)), {x, 0, 50}], x] (* _Vincenzo Librandi_, Jul 23 2014 *)
%t A245179 LinearRecurrence[{0,3,0,-2},{7,11,13,19},50] (* _Harvey P. Dale_, Mar 05 2015 *)
%o A245179 (Magma) &cat [[3*2^i+1,2^(i+2)+3]: i in [1..30]]; // _Bruno Berselli_, Jul 23 2014
%Y A245179 Essentially the union of A062709 and A181565. Cf. A245178.
%K A245179 nonn,easy
%O A245179 1,1
%A A245179 _N. J. A. Sloane_, Jul 17 2014