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%I #15 Feb 19 2021 05:55:41
%S 2,12,240,4032,1047552,16773120,4294901760,68719214592,17592181850112,
%T 72057593769492480,1152921503533105152,4722366482800925736960,
%U 1208925819613529663078400,19342813113829668748787712
%N a(n) = 2^(p - 2)*(2^p - 2), where p = prime(n).
%F a(n) = A020522(prime(n)-1). - _Michel Marcus_, Feb 18 2021
%e Prime(1)=2, so a(1) = 2^(2 - 2)*(2^2 - 2) = 2^0*(4-2) = 2.
%e Prime(2)=3, so a(2) = 2^(3 - 2)*(2^3 - 2) = 2^1*(8-2) = 12.
%t Table[2^(n-2) (2^n-2),{n,Prime[Range[20]]}] (* _Harvey P. Dale_, Aug 19 2014 *)
%Y Cf. A020522.
%K nonn
%O 1,1
%A _Juri-Stepan Gerasimov_, Aug 05 2008
%E Corrected and extended by _D. S. McNeil_, Mar 21 2009
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