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

0,5

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).

Links

Table of n, a(n) for n=0..54.

Example

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

Crossrefs

Diagonals give A026012, A123355, A123356.

Sequence in context: A107702 A174480 A111670 * A156540 A156582 A156953

Adjacent sequences: A123350 A123351 A123352 * A123354 A123355 A123356

Keyword

nonn,tabl

Author

N. J. A. Sloane, Oct 14 2006

Status

approved