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 A287682 #12 May 30 2017 05:35:31
%S A287682 4,6,18,30,198,306,462,702,1482,2550,3330,4422,5778,6102,6498,9042,
%T A287682 11178,11778,14418,15498,17298,17442,19458,20862,21582,22878,23322,
%U A287682 23550,25230,26622,26862,26910,27378,30210,34542,36738,38610,39006,39102,40350,40662
%N A287682 Triples of practical numbers: numbers n such that n-2, n, n+2 are all practical numbers.
%C A287682 Melfi proved that this sequence is infinite.
%H A287682 Amiram Eldar, <a href="/A287682/b287682.txt">Table of n, a(n) for n = 1..1000</a>
%H A287682 Giuseppe Melfi, <a href="http://members.unine.ch/giuseppe.melfi/articoli/smapoto.pdf">A survey on practical numbers</a>, Rend. Sem. Mat. Univ. Pol. Torino, 53, (1995), 347-359.
%H A287682 Giuseppe Melfi, <a href="http://www.dm.unipi.it/gauss-pages/melfi/public_html/trip.htmll">Triplets of practical numbers</a>
%t A287682 practicalQ[n_] := Module[{f, p, e, prod=1, ok=True}, If[n<1 || (n>1 && OddQ[n]), False, If[n==1, True, f=FactorInteger[n]; {p, e} = Transpose[f]; Do[If[p[[i]] > 1+DivisorSigma[1, prod], ok=False; Break[]]; prod=prod*p[[i]]^e[[i]], {i, Length[p]}]; ok]]];
%t A287682 a={}; p1=False; p2=False; k=2; While[Length[a]<100, p3=practicalQ[k]; If[p1 && p2 && p3, a=AppendTo[a,k-2]]; p1 = p2; p2 = p3; k+=2];a
%Y A287682 Cf. A005153, A209236, A287681, A287683.
%K A287682 nonn
%O A287682 1,1
%A A287682 _Amiram Eldar_, May 29 2017