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 A171127 #13 Jan 16 2022 08:19:09 %S A171127 4,6,9,20,28,30,42,44,45,52,63,66,68,76,78,92,99,100,102,114,116,117, %T A171127 124,138,140,148,150,153,164,171,172,174,186,188,196,207,210,212,220, %U A171127 222,225,236,244,246,258,260,261,268,279,282,284,292,294,308,315,316 %N A171127 Numbers k such that A169611(k) = 2. %C A171127 The asymptotic density of this sequence is 19/108. - _Amiram Eldar_, Jan 16 2022 %H A171127 Amiram Eldar, <a href="/A171127/b171127.txt">Table of n, a(n) for n = 1..10000</a> %t A171127 f[n_] := Plus @@ Last /@ Select[ FactorInteger@ n, 1 < #[[1]] < 4 &]; Select[ Range@ 317, f@# == 2 &] (* _Robert G. Wilson v_, Dec 19 2009) (* Extended beyond 150 by _R. J. Mathar_, Dec 09 2009 *) %Y A171127 Cf. A169611. %K A171127 nonn %O A171127 1,1 %A A171127 _Juri-Stepan Gerasimov_, Dec 04 2009 %E A171127 Extended beyond 150 by _R. J. Mathar_, Dec 09 2009