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 A193579 #33 Sep 08 2022 08:45:58
%S A193579 9,15,39,135,519,2055,8199,32775,131079,524295,2097159,8388615,
%T A193579 33554439,134217735,536870919,2147483655,8589934599,34359738375,
%U A193579 137438953479,549755813895,2199023255559,8796093022215,35184372088839,140737488355335,562949953421319,2251799813685255
%N A193579 a(n) = 2*4^n + 7.
%C A193579 Bisection of A168415 (odd part).
%H A193579 Vincenzo Librandi, <a href="/A193579/b193579.txt">Table of n, a(n) for n = 0..1000</a>
%H A193579 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (5,-4).
%F A193579 a(n) = 2^(2n + 1) + 7 = 3*(A020988(n) + 3).
%F A193579 From _Bruno Berselli_, Sep 20 2011: (Start)
%F A193579 G.f.: 3*(3 - 10*x)/((1 - x)*(1 - 4*x)).
%F A193579 a(n) = A085688(A016969(n)). (End)
%F A193579 E.g.f.: 7*exp(x) + 2*exp(4*x). - _Franck Maminirina Ramaharo_, Nov 07 2018
%t A193579 2*4^Range[0,30]+7 (* or *) LinearRecurrence[{5,-4},{9,15},30] (* _Harvey P. Dale_, Jun 13 2020 *)
%o A193579 (Magma) [2*4^n + 7: n in [0..30]]; // _Vincenzo Librandi_, Sep 30 2011
%o A193579 (PARI) a(n) = 2*4^n+7 \\ _Felix Fröhlich_, Nov 07 2018
%o A193579 (PARI) Vec(3*(3 - 10*x)/((1 - x)*(1 - 4*x)) + O(x^20)) \\ _Felix Fröhlich_, Nov 07 2018
%Y A193579 Cf. A168415, A020988.
%K A193579 nonn,easy
%O A193579 0,1
%A A193579 _Brad Clardy_, Sep 20 2011