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%I #16 Sep 08 2022 08:45:51
%S 25,81,1089,16641,4198401,67125249,17180131329,274878955521,
%T 70368760954881,288230377225453569,4611686022722355201,
%U 18889465931753458761729,4835703278462914745335809,77371252455353859367239681,19807040628566365873362698241
%N (2^p+1)^2 where p is prime.
%H Vincenzo Librandi, <a href="/A174623/b174623.txt">Table of n, a(n) for n = 1..200</a>
%F a(n) = (A098640(n))^2. - _R. J. Mathar_, Jul 06 2010
%e For p=2, (2^2+1)^2=25;
%e for p=3, (2^3+1)^2=81;
%e for p=5, (2^5+1)^2=1089.
%p A174623:=n->(2^ithprime(n)+1)^2: seq(A174623(n), n=1..20); # _Wesley Ivan Hurt_, Apr 18 2017
%t Table[(2^Prime[n] + 1)^2, {n, 30}] (* _Vincenzo Librandi_, Apr 29 2014 *)
%o (Magma) [(2^p+1)^2: p in [0..1000] |IsPrime(p)]
%K nonn
%O 1,1
%A _Vincenzo Librandi_, Apr 11 2010
%E Definition clarified by _Jon E. Schoenfield_, Jun 18 2010
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