A165925 Irregular triangle read by rows: square-full quadratic non-residues.

8, 8, 8, 8, 8, 12, 8, 12, 8, 12, 12, 8, 12, 8, 12, 18, 8, 12, 18, 8, 12, 20, 8, 18, 20, 8, 18, 20, 8, 12, 18, 20, 8, 18, 20, 24, 8, 12, 18, 20, 24, 12, 18, 20, 24, 27, 8, 12, 18, 27, 8, 12, 18, 20, 27, 28, 12, 24, 27, 8, 12, 18, 20, 24, 27, 28, 8, 18, 20, 24, 28, 32, 12, 20, 24, 27, 28

Offset: 9

Author

Christopher Hunt Gribble, Sep 30 2009

Keywords

• nonn
• tabf

Comments

The irregular triangle of numbers is:

..n....Square-full quadratic non-residues

..1....

..2....

..3....

..4....

..5....

..6....

..7....

..8....

..9.....8

.10.....8

.11.....8

.12.....8

.13.....8

.14....12

.15.....8.12

.16.....8.12

.17....12

.18.....8.12

.19.....8.12.18

.20.....8.12.18

.21.....8.12.20

.22.....8.18

.23....20

.24.....8.18.20

.25.....8.12.18.20

.26.....8.18.20.24

.27.....8.12.18.20.24

.28....12.18.20.24.27

.29.....8.12.18.27

.30.....8.12.18.20.27.28

.31....12.24.27

.32.....8.12.18.20.24.27.28

.33.....8.18.20.24.28.32

.34....12.20.24.27.28

Links

• C. H. Gribble, Flattened irregular triangle read by rows j = 9 to 200

Crossrefs

Cf. A096013.

Programs

Mathematica

Flatten[Table[Select[Complement[Range[n - 1], Mod[Range[n/2]^2, n]], ! SquareFreeQ[#] &], {n, 9, 34}]] (* T. D. Noe, Nov 22 2011 *)