A126886 Triangle read by rows, arising in enumeration of 4-trees by diameter.

1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 5, 6, 8, 7, 7, 5, 5, 3, 2, 1, 1, 1, 2, 7, 12, 23, 30, 42, 47, 55, 53, 53, 45, 40, 29, 23

Offset: 0

Author

N. J. A. Sloane, Aug 04 2007

Keywords

• nonn
• tabf

Comments

See reference for precise definition.

Examples

			Triangle begins:
1
1
1 1 1
1 1 2 1 1
1 2 5 6 8 7 7 5 5 3 2 1 1
1 2 7 12 23 30 42 47 55 53 53 45 40 29 23 ...
		

Links

• A. T. Balaban, J. W. Kennedy and L. V. Quintas, The number of alkanes having n carbons and a longest chain of length d, J. Chem. Education, 65 (1988), 304-313.

Crossrefs

Cf. A000602 (diagonal sums when rows are displaced by the appropriate amounts), A036437.