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Numbers of the form 2*p^e, with p an odd prime and e >= 2.
2

%I #13 Jun 18 2022 04:03:48

%S 18,50,54,98,162,242,250,338,486,578,686,722,1058,1250,1458,1682,1922,

%T 2662,2738,3362,3698,4374,4394,4418,4802,5618,6250,6962,7442,8978,

%U 9826,10082,10658,12482,13122,13718,13778,15842,18818,20402,21218,22898,23762,24334,25538,29282,31250,32258

%N Numbers of the form 2*p^e, with p an odd prime and e >= 2.

%C Conjecturally numbers k > 1 such that A047994(k) = A344005(k) (see A354928), and k is in A265128. See comments in A346608.

%H Amiram Eldar, <a href="/A354929/b354929.txt">Table of n, a(n) for n = 1..10000</a>

%F Sum_{n>=1} 1/a(n) = (A136141 - 1/2)/2 = 0.1365783345... - _Amiram Eldar_, Jun 18 2022

%t Select[Range[33000], IntegerExponent[#, 2] == 1 && CompositeQ[#/2] && PrimePowerQ[#/2] &] (* _Amiram Eldar_, Jun 18 2022 *)

%o (PARI) isA354929(n) = ((2==(n%4)) && (isprimepower(n/2)>1));

%Y Subsequence of A278568.

%Y Intersection of A265128 and A354928 (conjectured).

%Y Cf. A047994, A136141, A344005, A346608, A354924.

%K nonn

%O 1,1

%A _Antti Karttunen_, Jun 13 2022