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Numbers with a unique partition as the sum of 2 squares x^2 + y^2.
8

%I #18 Mar 24 2021 09:30:59

%S 0,1,2,4,5,8,9,10,13,16,17,18,20,26,29,32,34,36,37,40,41,45,49,52,53,

%T 58,61,64,68,72,73,74,80,81,82,89,90,97,98,101,104,106,109,113,116,

%U 117,121,122,128,136,137,144,146,148,149,153,157,160,162,164,173,178,180,181

%N Numbers with a unique partition as the sum of 2 squares x^2 + y^2.

%C A000161(a(n)) = 1. [_Reinhard Zumkeller_, Aug 16 2011]

%H Reinhard Zumkeller, <a href="/A125022/b125022.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A125021(n)/2.

%t Select[Range[0,200],Length@PowersRepresentations[#,2,2]==1&] (* _Giorgos Kalogeropoulos_, Mar 21 2021 *)

%o (Haskell)

%o import Data.List (elemIndices)

%o a125022 n = a125022_list !! (n-1)

%o a125022_list = elemIndices 1 a000161_list

%o -- _Reinhard Zumkeller_, Aug 16 2011

%Y Cf. A002145, A124982, A125021, A034026.

%Y Cf. A025284, A081324, A022544, A001481, A118882.

%K nonn

%O 1,3

%A _Artur Jasinski_, Nov 16 2006

%E Name edited by _Giorgos Kalogeropoulos_, Mar 21 2021