A123353 Triangle read by rows, giving Kekulé numbers for certain benzenoids (see the Cyvin-Gutman book for details).

1, 1, 1, 1, 2, 1, 1, 3, 6, 1, 1, 4, 20, 19, 1, 1, 5, 50, 155, 62, 1, 1, 6, 105, 805, 1315, 207, 1, 1, 7, 196, 3136, 15218, 11957, 704, 1, 1, 8, 336, 9996, 118188, 326053, 114972, 2431, 1, 1, 9, 540, 27468, 690480, 5355756, 7736092, 1157650, 8502, 1

Offset: 0

Author

N. J. A. Sloane, Oct 14 2006

Keywords

• nonn
• tabl

Examples

			Triangle begins:
  1
  1 1
  1 2 1
  1 3 6 1
  1 4 20 19 1
  1 5 50 155 62 1
  1 6 105 805 1315 207 1
  1 7 196 3136 15218 11957 704 1
  1 8 336 9996 118188 326053 114972 2431 1
  1 9 540 27468 690480 5355756 7736092 1157650 8502 1
  1 10 825 67320 3256308 60864012 282497568 199806100 12115220 30056 1
		

References

• S. J. Cyvin and I. Gutman, Kekulé structures in benzenoid hydrocarbons, Lecture Notes in Chemistry, No. 46, Springer, New York, 1988 (see p. 188).

Crossrefs

Diagonals give A026012, A123355, A123356.