A123722 - OEIS

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A123722

Values of n for which A000224(n)=Ceiling[(n+1)/3]; A000224(n) is the number of squares mod n.

1, 3, 4, 8, 9, 15, 21, 33, 35, 39, 51, 57, 69, 70, 87, 93, 111, 123, 129, 141, 159, 177, 183, 201, 213, 219, 237, 249, 267, 291, 303, 309, 321, 327, 339, 381, 393, 411, 417, 447, 453, 471, 489, 501, 519, 537, 543, 573, 579, 591, 597, 633, 669, 681, 687, 699, 717 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	COMMENTS	`Conjecture. If n>2 and a(n) is a multiple of 3, then a(n)/3 is a prime; further, all odd primes are given as a(n)/3 for some n. (This has been verified up to n=2000.)`
	CROSSREFS	`Cf. A000224, A123723.` `Sequence in context: A186775 A135276 A058074 * A200727 A096185 A137640` `Adjacent sequences: A123719 A123720 A123721 * A123723 A123724 A123725`
	KEYWORD	`nonn`
	AUTHOR	`John W. Layman (layman(AT)math.vt.edu), Oct 09 2006`

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Last modified February 15 21:56 EST 2012. Contains 205860 sequences.