A054018 -id:A054018 - cp's OEIS frontend

A054019 Square roots of A054018.

3, 1, 4, 3, 5, 4, 5, 7, 4, 1, 8, 11, 6, 9, 8, 13, 8, 6, 10, 15, 8, 6, 11, 6, 13, 7, 19, 15, 1, 12, 21, 21, 12, 16, 20, 14, 8, 21, 1, 12, 19, 8, 20, 21, 27, 8, 14, 12, 27, 10, 29, 27, 5, 20, 16, 35, 10, 27, 35, 31, 30, 29, 3, 12, 28, 5, 1, 35, 26, 10, 20, 37, 12, 33, 18, 43, 43, 45, 22

Offset: 1

Asher Auel, Jan 19 2000

nonn

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

Cf. A048050, A054013, A054017, A054018.

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

A054017 Chowla's function of n modulo n is a square (excluding 0's).

Original entry on oeis.org

14, 20, 39, 40, 46, 55, 80, 94, 100, 104, 117, 130, 155, 158, 183, 190, 200, 203, 291, 292, 295, 299, 320, 323, 334, 416, 430, 446, 464, 475, 488, 530, 539, 549, 567, 579, 583, 638, 650, 695, 718, 799, 873, 878, 890, 943, 955, 959, 964, 979, 1030, 1118

Offset: 1

Asher Auel, Jan 19 2000

nonn

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

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

Cf. A048050, A054013, A054018.

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

cp's OEIS Frontend

A054019 Square roots of A054018.

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