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 A047352 #46 Oct 16 2022 09:53:20
%S A047352 0,2,7,9,14,16,21,23,28,30,35,37,42,44,49,51,56,58,63,65,70,72,77,79,
%T A047352 84,86,91,93,98,100,105,107,112,114,119,121,126,128,133,135,140,142,
%U A047352 147,149,154,156,161,163,168,170
%N A047352 Numbers that are congruent to {0, 2} mod 7.
%C A047352 Numbers k such that k^2/7 + k*(k + 1)/14 = k*(3*k + 1)/14 is a nonnegative integer. - _Bruno Berselli_, Feb 14 2017
%H A047352 David Lovler, <a href="/A047352/b047352.txt">Table of n, a(n) for n = 1..1000</a>
%H A047352 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (1,1,-1).
%F A047352 a(n) = 7*n - a(n-1) - 12 with a(1)=0. Also: a(n) = a(n-1) + a(n-2) - a(n-3). - _Vincenzo Librandi_, Aug 05 2010
%F A047352 a(n+1) = Sum_{k>=0} A030308(n,k)*b(k) with b(0)=2 and b(k)=A005009(k-1) for k>0. - _Philippe Deléham_, Oct 17 2011
%F A047352 G.f.: x^2*(2 + 5*x)/((1 + x)*(1 - x)^2). - _R. J. Mathar_, Dec 04 2011
%F A047352 a(n) = floor((7/3)*floor(3*n/2)). - _Clark Kimberling_, Jul 04 2012
%F A047352 E.g.f.: 5 + ((14*x - 17)*exp(x) - 3*exp(-x))/4. - _David Lovler_, Aug 31 2022
%t A047352 LinearRecurrence[{1,1,-1},{0,2,7},50] (* _Harvey P. Dale_, Oct 16 2022 *)
%o A047352 (PARI) forstep(n=0,200,[2,5],print1(n", ")) \\ _Charles R Greathouse IV_, Oct 17 2011
%Y A047352 Cf. A005009, A030308.
%K A047352 nonn,easy
%O A047352 1,2
%A A047352 _N. J. A. Sloane_