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 A053639 #15 Sep 08 2022 08:45:00
%S A053639 4,4,6,8,13,22,37,64,114,205,373,683,1261,2341,4370,8192,15421,29128,
%T A053639 55189,104858,199729,381301,729445,1398102,2684355,5162221,9942054,
%U A053639 19173962,37025581,71582789,138547333,268435456,520602097
%N A053639 a(n) = ceiling(2^(n+1)/n).
%H A053639 Vincenzo Librandi, <a href="/A053639/b053639.txt">Table of n, a(n) for n = 1..1000</a>
%p A053639 A053639:=n->ceil(2^(n+1)/n): seq(A053639(n), n=1..40); # _Wesley Ivan Hurt_, Jan 19 2017
%t A053639 Table[Ceiling[2^(n+1)/n],{n,1,40}] (* _Vincenzo Librandi_, Dec 19 2011 *)
%o A053639 (Magma) [Ceiling(2^(n+1)/n): n in [1..40]]; // _Vincenzo Librandi_, Dec 19 2011
%o A053639 (PARI) vector(40, n, ceil(2^(n+1)/n) ) \\ _G. C. Greubel_, May 17 2019
%o A053639 (Sage) [ceil(2^(n+1)/n) for n in (1..40)] # _G. C. Greubel_, May 17 2019
%Y A053639 Cf. A053637, A053638.
%K A053639 nonn,easy
%O A053639 1,1
%A A053639 _N. J. A. Sloane_, Mar 23 2000