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 A179651 #20 Jun 29 2023 09:06:40
%S A179651 1,2,2,2,4,4,2,2,4,4,2,2,4,4,2,6,6,2,4,4,2,6,6,2,4,4,2,6,4,4,4,4,8,6,
%T A179651 2,4,8,4,6,6,4,2,6,8,4,12,4,2,2,4,4,2,6,4,4,4,6,6,12,4,4,4,6,2,4,4,8,
%U A179651 6,6,4,2,2,4,8,4,6,6,4,2,6,4,8,4,4,10,2,4,6,2,4,4,8,6,2,4,12,8,8,2,6,4,2,2
%N A179651 Difference between consecutive practical numbers.
%C A179651 Because the density of practical numbers is comparable to that of primes, it is natural to inquire whether certain results about prime numbers and their gaps carry over to practical numbers and their gaps. For example, it is known that lim inf a(n) = 2, which is comparable to the twin prime conjecture; and since the density of the practical numbers is zero, it follows that a(n) is unbounded. - _Hal M. Switkay_, Jan 21 2023
%H A179651 Hal M. Switkay, <a href="/A179651/b179651.txt">Table of n, a(n) for n = 1..9999</a>
%F A179651 a(n) = A005153(n+1) - A005153(n).
%e A179651 For n=3, this is 6-4=2.
%e A179651 For n=5, this is 12-8=4.
%t A179651 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]]]; s = Select[ Range@ 479, PracticalQ]; Rest@s - Most@s (* _Robert G. Wilson v_, Jul 23 2010 *)
%Y A179651 Cf. A005153.
%K A179651 easy,nonn
%O A179651 1,2
%A A179651 _Jason G. Wurtzel_, Jul 22 2010
%E A179651 a(20) onwards from _Robert G. Wilson v_, Jul 23 2010