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Semiprimes of the form floor(e^k).
1

%I #17 Sep 15 2024 01:52:43

%S 403,3269017,485165195,3584912846,26489122129,29048849665247,

%T 639843493530054949,114200738981568428366295718,

%U 66631762164108958342448140502408732626873,492345828601205839975486205911330449483779

%N Semiprimes of the form floor(e^k).

%H Giovanni Resta, <a href="/A117836/b117836.txt">Table of n, a(n) for n = 1..17</a>

%F A000149 Intersection A001358.

%e a(1) = 403 = floor(e^6) = 13 * 31.

%e a(2) = 3269017 = floor(e^15) = 773 * 4229.

%e a(3) = 485165195 = floor(e^20) = 5 * 97033039.

%e a(4) = 3584912846 = floor(e^22) = 2 * 1792456423.

%e a(5) = 26489122129 = floor(e^24) = 103 * 257175943.

%t Select[Table[Floor[Exp[k]],{k,100}],PrimeOmega[#]==2&] (* _James C. McMahon_, Sep 14 2024 *)

%Y Cf. A000040, A000149, A001358, A074496.

%K nonn

%O 1,1

%A _Jonathan Vos Post_, Apr 30 2006

%E a(6)-a(10) from _Giovanni Resta_, Jun 15 2016