login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A034799 Triangle of number of labeled trees by number of nodes and number of labels. 1
1, 1, 1, 1, 1, 1, 1, 2, 3, 3, 2, 4, 9, 16, 16, 3, 9, 26, 67, 125, 125, 6, 20, 75, 251, 680, 1296, 1296, 11, 48, 214, 888, 3135, 8716, 16807, 16807, 23, 115, 612, 3023, 13155, 47787, 134960, 262144, 262144, 47, 286, 1747, 10038, 51873, 232154, 858578, 2450309, 4782969, 4782969 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,8

REFERENCES

J. Riordan, An Introduction to Combinatorial Analysis, p. 138.

LINKS

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

Index entries for sequences related to trees

FORMULA

Reference gives generating function.

E.g.f.: r(x,y) - (1/2)*r(x,y)^2 + (1/2)*r(x^2) where r(x,y) is the e.g.f. for A008295 and r(x) is the o.g.f. for A000081. - Sean A. Irvine, Sep 04 2020

EXAMPLE

Triangle begins:

  1;

  1, 1;

  1, 1, 1;

  1, 2, 3, 3;

  2, 4, 9, 16, 16;

  ...

CROSSREFS

Cf. A000081, A008295, A034800.

Sequence in context: A309076 A343326 A073078 * A008985 A326699 A138652

Adjacent sequences:  A034796 A034797 A034798 * A034800 A034801 A034802

KEYWORD

nonn,tabl

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Sean A. Irvine, Sep 04 2020

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
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 23 21:27 EDT 2021. Contains 348217 sequences. (Running on oeis4.)