A122842 - OEIS

%I #20 Feb 18 2023 15:28:36

%S 1,3,9,27,15,243,729,45,6561,19683,135,177147,225,105,4782969,

%T 14348907,1215,675,387420489,3645,3486784401,10460353203,315,

%U 94143178827,3375,32805,2541865828329,6075,98415,68630377364883

%N Square roots of the odd indexed terms of A038547.

%C A038547(n) is the least number with exactly n odd divisors. For odd n these are perfect squares.

%H R. J. Mathar, <a href="/A122842/b122842.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = sqrt(A038547(2*n-1)).

%F a(n) = sqrt(A119265(2*n-1, 2*n-1)).

%F a(n) = 3^(n-1) for n = (p+1)/2, where p is an odd prime.

%F a(3*n+2) = 5*3^n for n = (p-1)/2, where p is an odd prime.

%e a(1) = 1 because A038547(1) = 1.

%e a(2) = 3 because A038547(3) = 9.

%e a(5) = 15 because A038547(9) = 225.

%t (* Function a038547[ ] is defined in A038547 *)

%t a122842[n_]:=Sqrt[a038547[2n-1]]

%t Map[a122842,Range[30]] (* _Hartmut F. W. Hoft_, Feb 07 2023 *)

%Y Cf. A038547, A121858, A001227, A005179, A119265.

%Y Cf. A007051, A070826, A002110.

%K nonn

%O 1,2

%A _Alexander Adamchuk_, Sep 13 2006, Sep 25 2006

%E More terms from _R. J. Mathar_, Sep 20 2006

%E Edited by _Hartmut F. W. Hoft_, Feb 07 2023