A123354 Triangle read by rows, giving Kekulé numbers for certain benzenoids (see the Cyvin-Gutman book for details).

1, 1, 1, 1, 3, 1, 1, 6, 9, 1, 1, 10, 40, 27, 1, 1, 15, 125, 272, 81, 1, 1, 21, 315, 1625, 1856, 243, 1, 1, 28, 686, 6993, 21250, 12672, 729, 1, 1, 36, 1344, 24010, 156411, 278125, 86528, 2187, 1, 1, 45, 2430, 69888, 847553, 3501873, 3640625, 590848, 6561, 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. 210).

Links

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

Example

Triangle begins:
  1
  1 1
  1 3 1
  1 6 9 1
  1 10 40 27 1
  1 15 125 272 81 1
  1 21 315 1625 1856 243 1
  1 28 686 6993 21250 12672 729 1
  1 36 1344 24010 156411 278125 86528 2187 1
  1 45 2430 69888 847553 3501873 3640625 590848 6561 1
  1 55 4125 179334 3667968 29950074 78413427 47656250 4034560 19683 1

Crossrefs

Diagonals give A000244, A123357, A123358.

Sequence in context: A371967 A202605 A298636 * A120247 A235113 A235116

Adjacent sequences: A123351 A123352 A123353 * A123355 A123356 A123357

Keyword

nonn,tabl,changed

Author

N. J. A. Sloane, Oct 14 2006

Status

approved