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 A051139 #15 Jul 04 2022 04:42:00
%S A051139 1,0,0,1,3,7,19,64,236,893,3489,14347,62429,285580,1362372,6749337,
%T A051139 34683211,184774851,1019351071,5813020060,34206071992,207391313189,
%U A051139 1294092695729,8302365433863,54713262186745,370027343460584,2565874205681368
%N A051139 a(n) = A000994(n+2) - A000995(n+2).
%H A051139 Reinhard Zumkeller, <a href="/A051139/b051139.txt">Table of n, a(n) for n = 0..100</a>
%F A051139 For recurrence see A000994 and A000995.
%e A051139 a(7) = 359 - 295 = 64.
%t A051139 a4[_?Negative] = 0; a4[n_] := a4[n] = 1 + Sum[ Binomial[n, k]*a4[k-2], {k, 2, n}]; a5[_?Negative] = 0; a5[n_] := a5[n] = n + Sum[ Binomial[n, k]*a5[k-2], {k, 2, n}]; a[n_] := a4[n] - a5[n]; Table[a[n], {n, 0, 26}] (* _Jean-François Alcover_, Oct 11 2013 *)
%o A051139 (Haskell)
%o A051139 a051139 n = a000994 (n + 2) - a000995 (n + 2)
%o A051139 -- _Reinhard Zumkeller_, Jun 02 2013
%Y A051139 Cf. A000994, A000995.
%K A051139 nonn,easy,eigen,nice
%O A051139 0,5
%A A051139 _N. J. A. Sloane_