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%I A181705 #15 May 12 2023 09:33:01
%S A181705 56,368,128768,2087936,8589344768,2199013818368,36893488108764397568,
%T A181705 904625697166532776746648320380374279912262923807289020860114158381451706368
%N A181705 Numbers of the form 2^(t-1)*(2^t-9), where 2^t-9 is prime.
%C A181705 Subsequence of A181595.
%C A181705 (Proof: Let m=2^(t-1)*(2^t-9) be the entry. By the multiplicative property of the sigma-function, sigma(m)=(2^t-1)*(2^t-8).
%C A181705 The abundance sigma(m)-2*m is therefore 8, and since all t involved are >=4, 8 is a divisor of m because 8 divides 2^(t-1).)
%t A181705 2^(#-1) (2^#-9)&/@Select[Range[3,130],PrimeQ[2^#-9]&] (* _Harvey P. Dale_, Oct 24 2011 *)
%Y A181705 Cf. A059610, A181595, A181701, A000396, A181703, A181704
%K A181705 nonn
%O A181705 1,1
%A A181705 _Vladimir Shevelev_, Nov 06 2010
%E A181705 Edited by _R. J. Mathar_, Sep 12 2011

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