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 A134019 #15 Nov 30 2015 09:42:38
%S A134019 1,2,4,11,46,227,1114,5231,23566,102827,438274,1836551,7601686,
%T A134019 31183427,127084234,515429471,2083077406,8396552027,33779262994,
%U A134019 135696871991,544528258726,2183337968627,8749031918554,35043178292111,140313885993646,561679104393227,2247987182714914,8995761194057831
%N A134019 Let P(A) be the power set of an n-element set A. Then a(n) = the number of pairs of elements {x,y} of P(A) for which either 0) x and y are intersecting but for which x is not a subset of y and y is not a subset of x, or 1) x = y.
%H A134019 Ross La Haye, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL12/LaHaye/lahaye5.html">Binary Relations on the Power Set of an n-Element Set</a>, Journal of Integer Sequences, Vol. 12 (2009), Article 09.2.6. [_Ross La Haye_, Feb 22 2009]
%H A134019 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (10,-35,50,-24).
%F A134019 a(n) = (1/2)(4^n - 3^(n+1) + 5*2^n - 1) = 3*StirlingS2(n+1,4) + StirlingS2(n+1,2) + 1.
%F A134019 G.f.: -(9*x^3-19*x^2+8*x-1) / ((x-1)*(2*x-1)*(3*x-1)*(4*x- 1)). [_Colin Barker_, Dec 10 2012]
%e A134019 a(3) = 11 because for P(A) = {{},{1},{2},{3},{1,2},{1,3},{2,3},{1,2,3}} we have for case 0 {{1,2},{1,3}}, {{1,2},{2,3}}, {{1,3},{2,3}} and we have for case 1 {{},{}}, {{1},{1}}, {{2},{2}}, {{3},{3}}, {{1,2},{1,2}}, {{1,3},{1,3}}, {{2,3},{2,3}}, {{1,2,3},{1,2,3}}.
%t A134019 Table[3 StirlingS2[n + 1, 4] + StirlingS2[n + 1, 2] + 1, {n, 0, 27}] (* _Michael De Vlieger_, Nov 30 2015 *)
%o A134019 (PARI) a(n) = (4^n - 3^(n+1) + 5*2^n - 1)/2; \\ _Michel Marcus_, Nov 30 2015
%Y A134019 Cf. A032263, A000079.
%K A134019 nonn,easy
%O A134019 0,2
%A A134019 _Ross La Haye_, Jan 10 2008
%E A134019 More terms from _Michael De Vlieger_, Nov 30 2015