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 A061761 #32 Dec 08 2024 12:23:09
%S A061761 0,3,7,13,23,41,75,141,271,529,1043,2069,4119,8217,16411,32797,65567,
%T A061761 131105,262179,524325,1048615,2097193,4194347,8388653,16777263,
%U A061761 33554481,67108915,134217781,268435511,536870969,1073741883,2147483709
%N A061761 a(n) = 2^n + 2*n - 1.
%H A061761 Harry J. Smith, <a href="/A061761/b061761.txt">Table of n, a(n) for n=0..200</a>
%H A061761 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (4,-5,2).
%F A061761 G.f.: x(3-5x)/((1-x)^2*(1-2x)). Binomial transform of 0,3,1,1,... (1 continued). - _R. J. Mathar_, Sep 17 2008
%F A061761 a(n) = A000225(n+1) - A005803(n), for n>0. In other words, for n>0, a(n) is the sum of the elements on the perimeter of a Pascal's triangle of depth (n+1). - _Ivan N. Ianakiev_, Aug 18 2016
%F A061761 E.g.f.: exp(x)*(exp(x) + 2*x - 1). - _Stefano Spezia_, Dec 08 2024
%e A061761 a(5) = 2^5 + 2*5 - 1 = 32 + 10 - 1 = 41. - _Michael B. Porter_, Aug 18 2016
%t A061761 Table[2^n+2*n-1,{n,0,60}] (* _Vladimir Joseph Stephan Orlovsky_, Feb 15 2011 *)
%o A061761 (PARI) a(n) = { 2^n + 2*n - 1 } \\ _Harry J. Smith_, Jul 27 2009
%Y A061761 Cf. A000225, A005803.
%K A061761 nonn
%O A061761 0,2
%A A061761 _Amarnath Murthy_, May 20 2001