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

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A052321 Number of rooted trees with a forbidden limb of length 3. 1
1, 1, 2, 3, 7, 15, 35, 81, 195, 473, 1171, 2924, 7396, 18848, 48446, 125311, 326145, 853188, 2242616, 5919197, 15683008, 41694334, 111195166, 297393668, 797475499, 2143631474, 5775002574, 15590201095, 42168292074, 114260967888 (list; graph; refs; listen; history; internal format)
OFFSET

1,3

COMMENTS

A rooted tree with a forbidden limb of length k is a rooted tree where the path from any leaf inward hits a branching node or the root within k steps.

LINKS

N. J. A. Sloane, Transforms

Index entries for sequences related to rooted trees

FORMULA

a(n) satisfies a=SHIFT_RIGHT(EULER(a-b)) where b(3)=1, b(k)=0 if k != 3.

CROSSREFS

Cf. A002955, A002988-A002992, A052318-A052329.

Sequence in context: A001932 A005909 A003006 * A114584 A039826 A161746

Adjacent sequences:  A052318 A052319 A052320 * A052322 A052323 A052324

KEYWORD

nonn

AUTHOR

Christian G. Bower (bowerc(AT)usa.net), Dec 15 1999.

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

Content is available under The OEIS End-User License Agreement .

Last modified February 16 02:51 EST 2012. Contains 205860 sequences.