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A000251 Number of trees of diameter 6.
(Formerly M2887 N1158)
0
1, 3, 11, 29, 74, 167, 367, 755, 1515, 2931, 5551, 10263, 18677, 33409, 59024, 102984, 177915, 304458, 516939, 871180, 1458882, 2428548, 4021670, 6627515, 10874462, 17770474, 28932739, 46943967, 75925797, 122433291, 196879385, 315759282, 505168033, 806290796, 1284034606, 2040485004, 3235965074, 5121801962, 8091411114, 12759606939, 20085832527, 31565046053, 49523414558, 77575278933, 121329065354, 189475663960, 295465391518, 460087656595, 715436020515, 1110994054004 (list; graph; refs; listen; history; text; internal format)
OFFSET

7,2

REFERENCES

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

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Table of n, a(n) for n=7..56.

Index entries for sequences related to trees

CROSSREFS

Sequence in context: A188475 A072610 A110954 * A159229 A239713 A122023

Adjacent sequences:  A000248 A000249 A000250 * A000252 A000253 A000254

KEYWORD

nonn

AUTHOR

N. J. A. Sloane

EXTENSIONS

More terms from Sean A. Irvine, Nov 21 2010

STATUS

approved

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Last modified March 25 19:30 EDT 2017. Contains 284082 sequences.