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 A023549 #14 Feb 02 2024 08:50:12
%S A023549 2,9,21,43,80,142,244,411,683,1125,1842,3004,4886,7933,12865,20847,
%T A023549 33764,54666,88488,143215,231767,375049,606886,982008,1588970,2571057,
%U A023549 4160109,6731251,10891448,17622790,28514332,46137219,74651651,120788973,195440730,316229812
%N A023549 Convolution of natural numbers >= 2 and Lucas numbers.
%H A023549 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (3,-2,-1,1)
%F A023549 G.f.: [x(2-x)(1+2x)]/[(1-x-x^2)(1-x)^2]. - _Ralf Stephan_, Apr 05 2004
%F A023549 a(n) = -13-3*n+5*A020701(n). - _R. J. Mathar_, May 22 2013
%t A023549 LinearRecurrence[{3, -2, -1, 1}, {2, 9, 21, 43}, 50] (* _Paolo Xausa_, Feb 02 2024 *)
%Y A023549 Cf. A020701.
%K A023549 nonn
%O A023549 1,1
%A A023549 _Clark Kimberling_