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%I #27 Jan 13 2022 15:11:11
%S 1,2,4,8,6,32,64,12,256,512,24,2048,36,30,16384,32768,96,72,262144,
%T 192,1048576,2097152,60,8388608,216,768,67108864,288,1536,536870912,
%U 1073741824,120,576,8589934592,6144,34359738368,68719476736,180,864
%N Smallest number whose square has exactly 2n+1 divisors.
%C Only squares have an odd number of divisors.
%F a(n) <= 2^n, where the equality holds if and only if n=0 or 2n+1 is prime. - _Jianing Song_, Aug 30 2021
%e a(4)=6 because it is the smallest number followed by 10,14,15,16,21,22,... whose squares have 2*4 + 1, i.e., 9 divisors.
%o (PARI) a(n) = {k = 1; while (numdiv(k^2) != (2*n+1), k++); return (k);} \\ _Michel Marcus_, Jul 27 2013
%Y Cf. A005179.
%Y Identical to A016017 shifted left.
%K nonn
%O 0,2
%A _Lekraj Beedassy_, May 31 2002
%E More terms from _Vladeta Jovovic_, Jun 05 2002
%E a(0) prepended by _Jianing Song_, Aug 30 2021
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