A353451 -id:A353451 - cp's OEIS frontend

A353532 T(n,m) is the number of non-congruent quadrilaterals with integer vertex coordinates (x1,1), (n,y2), (x3,m), (1,y4), 1 < x1, x3 < n, 1 < y2, y4 < m, m <= n, such that the 6 distances between the 4 vertices are distinct.

0, 0, 0, 0, 3, 1, 1, 7, 12, 11, 1, 11, 26, 52, 40, 4, 23, 50, 94, 147, 105, 4, 30, 69, 127, 198, 301, 190, 10, 49, 103, 192, 302, 444, 583, 379, 10, 58, 127, 244, 387, 576, 754, 1039, 616, 18, 84, 180, 329, 509, 756, 989, 1334, 1680, 987, 18, 94, 209, 389, 611, 910, 1203, 1618, 2052, 2581, 1426

Offset: 3

Hugo Pfoertner and Rainer Rosenthal, May 02 2022

T(n,m) is a triangle, read by rows.

			The triangle begins
    \ m 3   4    5    6    7    8    9   10
   n \-------------------------------------
   3 |  0,  |    |    |    |    |    |    |
   4 |  0,  0,   |    |    |    |    |    |
   5 |  0,  3,   1,   |    |    |    |    |
   6 |  1,  7,  12,  11,   |    |    |    |
   7 |  1, 11,  26,  52,  40,   |    |    |
   8 |  4, 23,  50,  94, 147, 105,   |    |
   9 |  4, 30,  69, 127, 198, 301, 190,   |
  10 | 10, 49, 103, 192, 302, 444, 583, 379
.
.
   4 | . C . . .    There are six squared distances.
   3 | . . . . .    They are arranged as follows:
   2 | D . . . B      AB-BC-CD-DA  (counterclockwise)
   1 | . A . . .      AC X DB      (across)
   y /----------    Here: AB = 3^2 + 1^2 = 10,
     x 1 2 3 4 5          BC = 13, CD = 5, DA = 2,
.                         AC =  9, DB = 16
      10-13-5-2  <==== yielding this
      9 X 16     <==== description
.
.
T(5,4) = a(5) = 3:
.
   4 | . X . . .     4 | . X . . .     4 | . . X . .
   3 | . . . . .     3 | . . . . X     3 | . . . . X
   2 | X . . . X     2 | X . . . .     2 | X . . . .
   1 | . X . . .     1 | . X . . .     1 | . X . . .
   y /----------     y /----------     y /----------
     x 1 2 3 4 5       x 1 2 3 4 5       x 1 2 3 4 5
.
      10-13-5-2          13-10-5-2          13-5-8-2
      9 X 16             9 X 17             10 X 17
.
T(5,5) = a(6) = A353447(5) = 1:
.
   5 | . . . X .
   4 | . . . . .
   3 | . . . . X    13-5-18-2
   2 | X . . . .    20 X 17
   1 | . X . . .
   y /----------
     x 1 2 3 4 5
.
T(6,3) = a(7) = 1:
.
   3 | . . . X . .
   2 | X . . . . X    17-5-10-2
   1 | . X . . . .    8 X 25
   y /------------
     x 1 2 3 4 5 6
.
T(6,4) = a(8) = 7:
.
   4 | . X . . . .   4 | . X . . . .   4 | . . X . . .   4 | . . . X . .
   3 | . . . . . .   3 | . . . . . X   3 | . . . . . .   3 | X . . . . .
   2 | X . . . . X   2 | X . . . . .   2 | X . . . . X   2 | . . . . . X
   1 | . X . . . .   1 | . X . . . .   1 | . X . . . .   1 | . X . . . .
   y /------------   y /------------   y /------------   y /------------
     x 1 2 3 4 5 6     x 1 2 3 4 5 6     x 1 2 3 4 5 6     x 1 2 3 4 5 6
.
       17-20-5-2         20-17-5-2         17-13-8-2         17-8-10-5
       9 X 25            9 X 26            10 X 25           13 X 26
.
   4 | . . . . X .   4 | . . X . . .   4 | . . X . . .
   3 | . . . . . .   3 | . . . . . .   3 | . . . . . X
   2 | X . . . . X   2 | X . . . . X   2 | X . . . . .
   1 | . X . . . .   1 | . . X . . .   1 | . . X . . .
   y /------------   y /------------   y /------------
     x 1 2 3 4 5 6     x 1 2 3 4 5 6     x 1 2 3 4 5 6
.
       17-5-20-2         10-13-8-5         13-10-8-5
       18 X 25           9 X 25            9 X 26
.

Rainer Rosenthal, Rows n = 3..100, flattened
Hugo Pfoertner, PARI program

Cf. A353447 (diagonal), A353449, A353450, A353451, A353533, A354700.

The general case without excluding the corners of the grid rectangle is covered in A354700 and A354701.

PARI
```
see Pfoertner link.
```

A353449 T(n,m) is the number of non-congruent quadrilaterals with integer vertex coordinates (x1,1), (n,y2), (x3,m), (1,y4), 1 < x1, x3 < n, 1 < y2, y4 < m, m <= n, such that the 6 distances between the 4 vertices are distinct and (x3-x1)*(y4-y2) > 0, where T(n,m) is a triangle read by rows.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 1, 2, 2, 0, 1, 8, 15, 12, 0, 3, 16, 27, 49, 29, 0, 7, 21, 44, 71, 103, 66, 0, 9, 30, 61, 106, 152, 216, 131, 0, 13, 41, 80, 145, 213, 298, 404, 245, 0, 17, 55, 106, 189, 279, 383, 507, 677, 373, 0, 22, 69, 135, 228, 345, 485, 641, 848, 1054, 576

Offset: 3

Rainer Rosenthal, May 13 2022

Property "(x3-x1)*(y4-y2) > 0" holds iff the diagonals (spokes) of the quadrilateral have unequal signs of their slope. In this case the spokes are tilted in the same direction (see example). The framed quadrilateral may be classified as "unisense" iff (x3-x1)*(y4-y2) > 0.

All quadrilaterals of A353532 are classified according to the sign of the product (x3-x1)*(y4-y2) as "all" = "unisense" (> 0) + "contrasense" (< 0) + "static" (= 0). The distinction is invariant under symmetry.

			The triangle begins
    \ m 3   4    5    6    7    8    9   10
   n \-------------------------------------
   3 |  0   |    |    |    |    |    |    |
   4 |  0,  0    |    |    |    |    |    |
   5 |  0,  0,   0    |    |    |    |    |
   6 |  0,  1,   2,   2    |    |    |    |
   7 |  0,  1,   8,  15,  12    |    |    |
   8 |  0,  3,  16,  27,  49,  29    |    |
   9 |  0,  7,  21,  44,  71, 103,  66    |
  10 |  0,  9,  30,  61, 106, 152, 216, 131
.
T(6,4) = 1 because of the third example for (6,4) in A353532:
  .
   4 | . . . C . .
   3 | D . . . . .     A = (x1,1) = (2,1), B = (6,y2) = (6,2)
   2 | . . . . . B     C = (x3,4) = (4,4), D = (1,y4) = (1,3)
   1 | . A . . . .
   y /------------      (x3-x1) * (y4-y2) = (4-2)*(3-2) > 0
     x 1 2 3 4 5 6
  .
Spokes AC and BD are tilted in the same direction, to the right. The signs of the slopes are unequal: AC has positive slope, and DB has negative slope.

Rainer Rosenthal, Rows n = 3..100, flattened

Cf. A353532 ("all"), A353450 ("contrasense"), A353451 ("static").

A353450 T(n,m) is the number of non-congruent quadrilaterals with integer vertex coordinates (x1,1), (n,y2), (x3,m), (1,y4), 1 < x1, x3 < n, 1 < y2, y4 < m, m <= n, such that the 6 distances between the 4 vertices are distinct and (x3-x1)*(y4-y2) < 0, where T(n,m) is a triangle read by rows.

Original entry on oeis.org

0, 0, 0, 0, 1, 1, 0, 0, 4, 5, 0, 2, 8, 18, 16, 0, 5, 14, 28, 50, 36, 0, 7, 23, 42, 75, 109, 77, 0, 10, 34, 65, 110, 157, 223, 143, 0, 14, 45, 89, 151, 223, 314, 423, 265, 0, 18, 58, 116, 186, 274, 386, 519, 684, 400, 0, 23, 73, 145, 239, 355, 491, 652, 870, 1069, 622

Offset: 3

Rainer Rosenthal, May 13 2022

Property "(x3-x1)*(y4-y2) < 0" holds iff the diagonals (spokes) of the quadrilateral are concurrent, i.e., their slopes are both positive or both negative. In this case the spokes are tilted in a different sense: clockwise and counterclockwise (see example). The framed quadrilateral may be classified as "contrasense" iff (x3-x1)*(y4-y2) < 0.

			The triangle begins
    \ m 3   4    5    6    7    8    9   10
   n \-------------------------------------
   3 |  0   |    |    |    |    |    |    |
   4 |  0,  0    |    |    |    |    |    |
   5 |  0,  1,   1    |    |    |    |    |
   6 |  0,  0,   4,   5    |    |    |    |
   7 |  0,  2,   8,  18,  16    |    |    |
   8 |  0,  5,  14,  28,  50,  36    |    |
   9 |  0,  7,  23,  42,  75, 109,  77    |
  10 |  0, 10,  34,  65, 110, 157, 223, 143
.
T(5,4) = 1 because of the third example for (5,4) in A353532.
  .
   4 | . . C . .
   3 | . . . . B     A = (x1,1) = (2,1), B = (5,y2) = (5,3)
   2 | D . . . .     C = (x3,4) = (3,4), D = (1,y4) = (1,2)
   1 | . A . . .
   y /----------      (x3-x1) * (y4-y2) = (3-2)*(2-3) < 0
     x 1 2 3 4 5
  .
Spokes AC and BD are tilted in different directions ("contrasense"). AC has positive slope and is tilted to the right (clockwise), DB also has same sign of slope, but is tilted to the left (counterclockwise).
  .
T(5,5) = 1 because of the third example for (5,5) in A353532.
  .
   5 | . . . C .
   4 | . . . . .     A = (x1,1) = (2,1), B = (5,y2) = (5,3)
   3 | . . . . B     C = (x3,5) = (4,5), D = (1,y4) = (1,2)
   2 | D . . . .
   1 | . A . . .     (x3-x1) * (y4-y2) = (4-2)*(2-3) < 0
   y /----------
     x 1 2 3 4 5
  .
Spokes AC and DB are tilted in different directions ("contrasense") like in the example before.

Rainer Rosenthal, Rows n = 3..100, flattened

Cf. A353532 ("all"), A353449 ("unisense"), A353451 ("static").

cp's OEIS Frontend

A353532 T(n,m) is the number of non-congruent quadrilaterals with integer vertex coordinates (x1,1), (n,y2), (x3,m), (1,y4), 1 < x1, x3 < n, 1 < y2, y4 < m, m <= n, such that the 6 distances between the 4 vertices are distinct.

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A353449 T(n,m) is the number of non-congruent quadrilaterals with integer vertex coordinates (x1,1), (n,y2), (x3,m), (1,y4), 1 < x1, x3 < n, 1 < y2, y4 < m, m <= n, such that the 6 distances between the 4 vertices are distinct and (x3-x1)*(y4-y2) > 0, where T(n,m) is a triangle read by rows.

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A353450 T(n,m) is the number of non-congruent quadrilaterals with integer vertex coordinates (x1,1), (n,y2), (x3,m), (1,y4), 1 < x1, x3 < n, 1 < y2, y4 < m, m <= n, such that the 6 distances between the 4 vertices are distinct and (x3-x1)*(y4-y2) < 0, where T(n,m) is a triangle read by rows.

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