A366479 Irregular triangle T(n,k) (n >= 0, k >= 2) read by rows. Consider the planar graph formed from an equilateral triangle with n equally spaced points placed on each edge, as discussed in A092867(n+1). Then T(n,k) is the number of interior points where exactly k chords cross.
0, 3, 1, 42, 7, 123, 37, 6, 444, 90, 6, 3, 1053, 138, 33, 12, 1, 2145, 285, 63, 15, 0, 3, 4173, 481, 72, 24, 12, 6774, 790, 165, 30, 9, 3, 6, 10698, 1270, 183, 75, 24, 6, 6, 16827, 1584, 393, 102, 6, 12, 6, 3, 25746, 2220, 339, 135, 40, 12, 6, 6, 35052, 3084, 684, 177, 42, 18, 6, 9, 6
Offset: 0
Examples
Triangle begins: 0; 3, 1; 42, 7; 123, 37, 6; 444, 90, 6, 3; 1053, 138, 33, 12, 1; 2145, 285, 63, 15, 0, 3; 4173, 481, 72, 24, 12; 6774, 790, 165, 30, 9, 3, 6; 10698, 1270, 183, 75, 24, 6, 6; 16827, 1584, 393, 102, 6, 12, 6, 3; 25746, 2220, 339, 135, 40, 12, 6, 6; 35052, 3084, 684, 177, 42, 18, 6, 9, 6; 51378, 3667, 657, 237, 87, 30, 3, 0, 6; 67287, 5101, 1080, 255, 96, 21, 18, 15, 6; 87183, 6943, 1206, 393, 117, 57, 36, 24, 0, 0, 3; 113682, 8478, 1761, 486, 150, 27, 24, 30, 0, 15; 152460, 9927, 1557, 522, 180, 33, 51, 18, 12, 0, 1; 187131, 12585, 2559, 678, 180, 54, 24, 3, 24, 15, 6; 240942, 14190, 2358, 690, 318, 54, 42, 25, 12, 0, 15; 288459, 17866, 3372, 990, 342, 75, 48, 9, 36, 30, 0, 6; ...
Links
- Scott R. Shannon, Image for n = 1.
- Scott R. Shannon, Image for n = 2.
- Scott R. Shannon, Image for n = 3.
- Scott R. Shannon, Image for n = 4.
- Scott R. Shannon, Image for n = 5.
- Scott R. Shannon, Image for n = 10.
