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 A047207 #47 Sep 08 2022 08:44:56
%S A047207 0,1,3,4,5,6,8,9,10,11,13,14,15,16,18,19,20,21,23,24,25,26,28,29,30,
%T A047207 31,33,34,35,36,38,39,40,41,43,44,45,46,48,49,50,51,53,54,55,56,58,59,
%U A047207 60,61,63,64,65,66,68,69,70,71,73,74,75,76,78,79,80,81,83,84
%N A047207 Numbers that are congruent to {0, 1, 3, 4} mod 5.
%C A047207 Numbers not ending in 2 or 7. - _Bruno Berselli_, Oct 30 2017
%H A047207 Vincenzo Librandi, <a href="/A047207/b047207.txt">Table of n, a(n) for n = 1..8000</a>
%H A047207 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,1,-1).
%F A047207 a(n) = floor((5*n-3)/4). - _Gary Detlefs_, Mar 06 2010
%F A047207 G.f.: x^2*(1 + 2*x + x^2 + x^3) / ( (1 + x)*(x^2 + 1)*(x - 1)^2 ). - _R. J. Mathar_, Oct 08 2011
%F A047207 a(n+1) = Sum_{k>=0} A030308(n,k)*b(k) with b(0)=1, b(1)=3, b(k)=5*2^(k-2) for k>1. - _Philippe Deléham_, Oct 17 2011
%F A047207 From _Wesley Ivan Hurt_, May 30 2016: (Start)
%F A047207 a(n) = a(n-1) + a(n-4) - a(n-5) for n>5.
%F A047207 a(n) = (10*n-9-i^(2*n)+(1-i)*i^(-n)+(1+i)*i^n)/8, where i=sqrt(-1).
%F A047207 a(2*k) = A047209(k), a(2*k-1) = A047218(k). (End)
%F A047207 E.g.f.: (4 - sin(x) + cos(x) + (5*x - 4)*sinh(x) + 5*(x - 1)*cosh(x))/4. - _Ilya Gutkovskiy_, May 30 2016
%F A047207 Sum_{n>=2} (-1)^n/a(n) = log(5)/4 + 3*sqrt(5)*log(phi)/10 + sqrt(1-2/sqrt(5))*Pi/10, where phi is the golden ratio (A001622). - _Amiram Eldar_, Dec 07 2021
%p A047207 seq(floor((5*n-3)/4), n=1..57); # _Gary Detlefs_, Mar 06 2010
%t A047207 Flatten[Table[5*n + {0, 1, 3, 4}, {n, 0, 20}]] (* _T. D. Noe_, Nov 12 2013 *)
%t A047207 LinearRecurrence[{1,0,0,1,-1},{0,1,3,4,5},100] (* _Harvey P. Dale_, Jan 31 2022 *)
%o A047207 (PARI) forstep(n=0,99,[1,2,1,1],print1(n", ")) \\ _Charles R Greathouse IV_, Oct 17 2011
%o A047207 (Magma) [n : n in [0..100] | n mod 5 in [0, 1, 3, 4]]; // _Wesley Ivan Hurt_, May 30 2016
%Y A047207 Cf. A001622, A030308, A047209, A047218.
%K A047207 nonn,easy
%O A047207 1,3
%A A047207 _N. J. A. Sloane_