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A165916 Irregular triangle read by rows: squarefree quadratic non-residues. 3
2, 2, 3, 2, 3, 2, 5, 3, 5, 6, 2, 3, 5, 6, 7, 2, 3, 5, 6, 2, 3, 7, 2, 6, 7, 10, 2, 3, 5, 6, 7, 10, 11, 2, 5, 6, 7, 11, 3, 5, 6, 10, 13, 2, 3, 5, 7, 11, 13, 14, 2, 3, 5, 6, 7, 10, 11, 13, 14, 15, 3, 5, 6, 7, 10, 11, 14, 2, 3, 5, 6, 11, 14, 15, 17, 2, 3, 10, 13, 14, 15 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,1

COMMENTS

The irregular triangle of numbers is:

..n....Squarefree quadratic non-residues

..1....

..2....

..3....2

..4....2..3

..5....2..3

..6....2..5

..7....3..5..6

..8....2..3..5..6..7

..9....2..3..5..6

.10....2..3..7

.11....2..6..7.10

.12....2..3..5..6..7.10.11

.13....2..5..6..7.11

.14....3..5..6.10.13

.15....2..3..5..7.11.13.14

.16....2..3..5..6..7.10.11.13.14.15

.17....3..5..6..7.10.11.14

.18....2..3..5..6.11.14.15.17

.19....2..3.10.13.14.15

LINKS

C. H. Gribble, Flattened irregular triangle read by rows j = 3 to 200

MATHEMATICA

Flatten[Table[Select[Complement[Range[n - 1], Mod[Range[n/2]^2, n]], SquareFreeQ], {n, 3, 30}]] (* T. D. Noe, Nov 22 2011 *)

CROSSREFS

Cf. A096013.

Sequence in context: A105560 A331597 A339502 * A096013 A072380 A144910

Adjacent sequences:  A165913 A165914 A165915 * A165917 A165918 A165919

KEYWORD

nonn,tabf

AUTHOR

Christopher Hunt Gribble, Sep 30 2009

EXTENSIONS

Minor edit by Christopher Hunt Gribble, Oct 05 2009

STATUS

approved

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Last modified January 18 05:18 EST 2021. Contains 340250 sequences. (Running on oeis4.)