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

0,8

Comments

See reference for precise definition.

Links

Table of n, a(n) for n=0..37.

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.

Example

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 ...

Crossrefs

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

Sequence in context: A308035 A336479 A221131 * A179272 A264753 A165680

Adjacent sequences: A126883 A126884 A126885 * A126887 A126888 A126889

Keyword

nonn,tabf

Author

N. J. A. Sloane, Aug 04 2007

Status

approved