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A049232 indexed by A000040.
2

%I #15 Aug 26 2024 02:00:29

%S 1,4,9,14,15,18,21,22,25,36,39,40,48,53,59,65,67,70,72,73,74,82,85,88,

%T 99,101,110,114,122,125,127,129,130,137,143,146,147,155,158,168,174,

%U 177,180,181,188,194,198,200,202,204,213,216,219,220,224,226,229,235

%N A049232 indexed by A000040.

%C The asymptotic density of this sequence is 1 - 2 * Product_{p prime} (1-1/(p*(p-1))) = 1 - 2 * A005596 = 0.252088... - _Amiram Eldar_, Feb 28 2021

%H Amiram Eldar, <a href="/A091880/b091880.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = k such that A000040(k) = A049232(n).

%t Select[Range[100], ! SquareFreeQ[Prime[ # ] + 2] &] (* _Zak Seidov_, Oct 28 2008 *)

%Y Cf. A000040, A005596, A049232.

%K easy,nonn

%O 1,2

%A _Ray Chandler_, Feb 15 2004