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 A116427 #11 Sep 02 2024 13:04:15
%S A116427 1,3,13,50,200,726,2613,9061,30779,102637,338230,1102674,3566001,
%T A116427 11455355,36597558,116395587,368749900,1164407829,3666312894,
%U A116427 11515047829,36085395700,112857846859,352329509934,1098136237818
%N A116427 The number of n-almost primes less than or equal to 6^n, starting with a(0)=1.
%t A116427 AlmostPrimePi[k_Integer, n_] := Module[{a, i}, a[0] = 1; If[k == 1, PrimePi[n], Sum[PrimePi[n/Times @@ Prime[ Array[a, k - 1]]] - a[k - 1] + 1, Evaluate[ Sequence @@ Table[{a[i], a[i - 1], PrimePi[(n/Times @@ Prime[Array[a, i - 1]])^(1/(k - i + 1))]}, {i, k - 1}]] ]]]; (* _Eric W. Weisstein_, Feb 07 2006 *)
%t A116427 Join[{1},Table[AlmostPrimePi[n, 6^n], {n, 21}]]
%Y A116427 Cf. A078840, A078841, A078842, A116432, A078843, A116426, A078844, A116427, A078845, A116428, A116429, A116430, A078846, A116431.
%K A116427 nonn
%O A116427 0,2
%A A116427 _Robert G. Wilson v_, Feb 10 2006
%E A116427 a(22)-a(23) from _Donovan Johnson_, Oct 01 2010