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 A141722 #28 Apr 25 2024 09:26:52
%S A141722 1,25,121,505,2041,8185,32761,131065,524281,2097145,8388601,33554425,
%T A141722 134217721,536870905,2147483641,8589934585,34359738361,137438953465,
%U A141722 549755813881,2199023255545,8796093022201,35184372088825,140737488355321,562949953421305
%N A141722 a(n) = 8*4^n - 7.
%H A141722 G. C. Greubel, <a href="/A141722/b141722.txt">Table of n, a(n) for n = 0..1000</a> (terms 0..200 from Vincenzo Librandi)
%H A141722 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (5,-4).
%F A141722 a(n) = 4*a(n-1) + 21.
%F A141722 G.f.: (1+20*x)/((1-x)*(1-4*x)). - _R. J. Mathar_, Sep 13 2008
%F A141722 a(n) = 10*A000975(2n) + A000975(2n+1). - _Paul Curtz_, Sep 17 2008
%F A141722 From _G. C. Greubel_, Sep 30 2017: (Start)
%F A141722 a(n) = 5*a(n-1) - 4*a(n-2).
%F A141722 E.g.f.: 8*exp(4*x) - 7*exp(x). (End)
%p A141722 A141722:=n->8*4^n-7; seq(A141722(n), n=0..30); # _Wesley Ivan Hurt_, Feb 15 2014
%t A141722 Table[8*4^n-7, {n, 0, 30}] (* _Wesley Ivan Hurt_, Feb 15 2014 *)
%o A141722 (Magma) [8*4^n-7: n in [0..30]]; // _Vincenzo Librandi_, May 31 2011
%o A141722 (PARI) x='x+O('x^50); Vec((1+20*x)/((1-x)*(1-4*x))) \\ _G. C. Greubel_, Sep 30 2017
%Y A141722 Cf. A000975.
%K A141722 nonn,easy
%O A141722 0,2
%A A141722 _Paul Curtz_, Sep 12 2008
%E A141722 Edited by _N. J. A. Sloane_, Sep 13 2008
%E A141722 More terms from _R. J. Mathar_, Sep 13 2008
%E A141722 More terms from _Vincenzo Librandi_, May 31 2011
%E A141722 Better name (using formula from _R. J. Mathar_) from _Joerg Arndt_, Feb 16 2014