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 A175976 #37 Mar 08 2025 12:13:55
%S A175976 2,2,11,56,245,1010,4079,16364,65513,262118,1048547,4194272,16777181,
%T A175976 67108826,268435415,1073741780,4294967249,17179869134,68719476683,
%U A175976 274877906888,1099511627717,4398046511042,17592186044351,70368744177596,281474976710585,1125899906842550
%N A175976 a(n) = 4^n - 3*n + 1.
%H A175976 Vincenzo Librandi, <a href="/A175976/b175976.txt">Table of n, a(n) for n = 0..250</a>
%H A175976 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (6,-9,4).
%F A175976 G.f.: (-2+10*x-17*x^2)/((4*x-1)*(x-1)^2).
%F A175976 From _Bruno Berselli_, Nov 04 2010: (Start)
%F A175976 a(n) - 6*a(n-1) + 9*a(n-2) - 4*a(n-3) = 0 for n > 2.
%F A175976 a(n) = A158879(n) - A131098(n+1) (n > 0). (End)
%F A175976 E.g.f.: exp(x)*(1 - 3*x + exp(3*x)). - _Elmo R. Oliveira_, Mar 07 2025
%e A175976 a(1)=4-3+1=2. a(2)=16-6+1=11.
%p A175976 A175976 := proc(n) 4^n-3*n+1 ; end proc:
%t A175976 Table[4^n-3n+1,{n,0,30}] (* or *) LinearRecurrence[{6,-9,4},{2,2,11},30] (* _Harvey P. Dale_, Jul 07 2013 *)
%o A175976 (Magma) [4^n-3*n+1: n in [0..30]]; // _Vincenzo Librandi_, Mar 20 2014
%Y A175976 Cf. A131098, A158879.
%K A175976 nonn,easy
%O A175976 0,1
%A A175976 _Vincenzo Librandi_, Nov 02 2010
%E A175976 G.f., program and link to recurrences from _R. J. Mathar_, Nov 03 2010