login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A034853 Triangle giving number of trees with n >= 3 nodes and diameter d>=2. 8
1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 2, 5, 2, 1, 1, 3, 8, 7, 3, 1, 1, 3, 14, 14, 11, 3, 1, 1, 4, 21, 32, 29, 14, 4, 1, 1, 4, 32, 58, 74, 42, 19, 4, 1, 1, 5, 45, 110, 167, 128, 66, 23, 5, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

3,8

LINKS

R. J. Mathar, Table of n, a(n) for n = 3..212

B. D. McKay, Lists of Trees sorted by diameter and Homeomorphically irreducible trees, with <= 22 nodes.

B. D. McKay, Lists of Trees sorted by diameter and Homeomorphically irreducible trees, with <= 22 nodes. [Cached copy of top page only, pdf file, no active links, with permission]

J. Riordan, Enumeration of trees by height and diameter, IBM J. Res. Dev. 4 (1960), 473-478.

J. Riordan, The enumeration of trees by height and diameter, IBM Journal 4 (1960), 473-478. (Annotated scanned copy)

Index entries for sequences related to trees

FORMULA

Reference gives recurrence.

EXAMPLE

   1

   1    1

   1    1    1

   1    2    2    1

   1    2    5    2    1

   1    3    8    7    3    1

   1    3   14   14   11    3    1

   1    4   21   32   29   14    4    1

   1    4   32   58   74   42   19    4    1

   1    5   45  110  167  128   66   23    5    1

   1    5   65  187  367  334  219   88   29    5    1

   1    6   88  322  755  850  645  328  123   34    6    1

CROSSREFS

Cf. A000055 (row sums), A283826, A000094 (diameter 4), A000147 (diameter 5), A000251 (diameter 6), A000550 (diameter 7), A000306 (diameter 8).

Sequence in context: A070166 A131373 A245185 * A242093 A244006 A110283

Adjacent sequences:  A034850 A034851 A034852 * A034854 A034855 A034856

KEYWORD

nonn,tabl,easy,nice

AUTHOR

N. J. A. Sloane.

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified November 17 19:09 EST 2018. Contains 317276 sequences. (Running on oeis4.)