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A054018 Squares mentioned in A054017. 3
9, 1, 16, 9, 25, 16, 25, 49, 16, 1, 64, 121, 36, 81, 64, 169, 64, 36, 100, 225, 64, 36, 121, 36, 169, 49, 361, 225, 1, 144, 441, 441, 144, 256, 400, 196, 64, 441, 1, 144, 361, 64, 400, 441, 729, 64, 196, 144, 729, 100, 841, 729, 25, 400, 256, 1225, 100, 729, 1225 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

If Chowla's function of n read (modulo n) is a nonzero square, print this square.

Chowla's function (A048050) = sum of divisors of n except 1 and n.

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

MATHEMATICA

chowla[n_] := DivisorSigma[1, n] - n - 1; aQ[n_] := (c = chowla[n]) > 0 && IntegerQ @ Sqrt @ Mod[c, n]; Mod[chowla[#], #] & /@ Select[Range[1000], aQ] (* Amiram Eldar, Aug 28 2019 *)

CROSSREFS

Cf. A048050, A054013, A054017, A054019.

Sequence in context: A145966 A349143 A014721 * A342637 A010170 A317051

Adjacent sequences:  A054015 A054016 A054017 * A054019 A054020 A054021

KEYWORD

nonn

AUTHOR

Asher Auel (asher.auel(AT)reed.edu), Jan 19 2000

STATUS

approved

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Last modified May 28 15:04 EDT 2022. Contains 354115 sequences. (Running on oeis4.)