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 A027540 #22 Sep 08 2022 08:44:49
%S A027540 3,16,55,156,399,960,2223,5020,11143,24432,53079,114492,245535,524032,
%T A027540 1113823,2358972,4980375,10485360,22019655,46136860,96468463,
%U A027540 201326016,419429775,872414556,1811938599,3758095600,7784627383,16106126460,33285995583,68719475712
%N A027540 Second diagonal of A027537.
%H A027540 Vincenzo Librandi, <a href="/A027540/b027540.txt">Table of n, a(n) for n = 2..1000</a>
%F A027540 Numerators of sequence a[ n, n-1 ] in (a[ i, j ])^2 where a[ i, j ] = A(i, j)/i! if j <= i, 0 if j > i.
%F A027540 a(n) = (n+1)*(2^n - n - 1). - _Vladeta Jovovic_, Aug 18 2002
%F A027540 G.f.: x^2*(-3+5*x)/((2*x-1)^2*(x-1)^3). - Maksym Voznyy (voznyy(AT)mail.ru), Aug 14 2009; corrected by _R. J. Mathar_, Sep 16 2009
%F A027540 a(n) = Sum_{k=0..n} Sum_{i=0..n} (i-k) * C(n-k,i-2). - _Wesley Ivan Hurt_, Sep 19 2017
%t A027540 Table[(n + 1) (2^n - n - 1), {n, 2, 35}] (* _Vincenzo Librandi_, Sep 04 2017 *)
%o A027540 (Magma) [(n+1)*(2^n-n-1): n in [2..30]]; // _Vincenzo Librandi_, Sep 04 2017
%Y A027540 Cf. A027537.
%K A027540 nonn,easy
%O A027540 2,1
%A A027540 _Olivier Gérard_
%E A027540 More terms from _Vladeta Jovovic_, Aug 18 2002