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A303704 Numbers k such that all coprime quadratic residues modulo k are squares. 0
1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 16, 20, 21, 24, 28, 40, 48, 56, 60, 72, 88, 120, 168, 240, 840 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Numbers k such that A046073(k) = A057828(k).

There are exactly 25 members in this sequence and this is the full list. Note that for other k, A046073(k) > A057828(k).

LINKS

Table of n, a(n) for n=1..25.

EXAMPLE

All coprime quadratic residues modulo 21 are 1, 4, 16 and they are all squares, so 21 is a term.

All coprime quadratic residues modulo 840 are 1, 121, 169, 289, 361, 529 and they are all squares, so 840 is a term.

249 == 23^2 is a coprime quadratic residue modulo 280 but 249 is not a square number, so 280 is not a term.

CROSSREFS

Cf. A046073, A057828, A214583.

Sequence in context: A281624 A242441 A064481 * A067939 A067784 A018744

Adjacent sequences:  A303701 A303702 A303703 * A303705 A303706 A303707

KEYWORD

nonn,fini,full

AUTHOR

Jianing Song, Apr 29 2018

STATUS

approved

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Last modified November 16 12:40 EST 2018. Contains 317272 sequences. (Running on oeis4.)