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A125022 Numbers with a unique partition as the sum of 2 squares x^2 + y^2. 7
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, 58, 61, 64, 68, 72, 73, 74, 80, 81, 82, 89, 90, 97, 98, 101, 104, 106, 109, 113, 116, 117, 121, 122, 128, 136, 137, 144, 146, 148, 149, 153, 157, 160, 162, 164, 173, 178, 180, 181 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

A000161(a(n)) = 1. [Reinhard Zumkeller, Aug 16 2011]

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

FORMULA

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

MATHEMATICA

Select[Range[0, 200], Length@PowersRepresentations[#, 2, 2]==1&] (* Giorgos Kalogeropoulos, Mar 21 2021 *)

PROG

(Haskell)

import Data.List (elemIndices)

a125022 n = a125022_list !! (n-1)

a125022_list = elemIndices 1 a000161_list

-- Reinhard Zumkeller, Aug 16 2011

CROSSREFS

Cf. A002145, A124982, A125021, A034026.

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

Sequence in context: A248151 A245226 A034026 * A069011 A101185 A045702

Adjacent sequences:  A125019 A125020 A125021 * A125023 A125024 A125025

KEYWORD

nonn

AUTHOR

Artur Jasinski, Nov 16 2006

EXTENSIONS

Name edited by Giorgos Kalogeropoulos, Mar 21 2021

STATUS

approved

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Last modified September 16 08:18 EDT 2021. Contains 347469 sequences. (Running on oeis4.)