Statements (25)
| Predicate | Object |
|---|---|
| gptkbp:instanceOf |
gptkb:integer_sequence
|
| gptkbp:author |
gptkb:N._J._A._Sloane
|
| gptkbp:citation |
gptkb:OEIS_A000108
gptkb:OEIS_A001047 OEIS A000055 OEIS A000081 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995. F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, 1973, p. 22. |
| gptkbp:field |
gptkb:combinatorics
|
| gptkbp:first_terms |
1
|
| gptkbp:form |
a(n) = Sum_{k=1..n} binomial(n-1, k-1) * a(n-k)
|
| gptkbp:hasKeyword |
easy
nice nonn |
| gptkbp:hasOEISId |
gptkb:A006005
|
| gptkbp:maintainedBy |
gptkb:OEIS_Foundation
|
| gptkbp:offset |
1
|
| gptkbp:relatedTo |
rooted trees
height of trees |
| gptkbp:sequence |
1, 1, 2, 4, 9, 20, 48, 115, 286, 719, 1842, 4766, 12486, 32973, 87733, 235381, 635626, 1726566, 4714356, 12902448, 35481720, 97840503, 270747514, 751065460, 2080123496, 5765988805, 16096452980, 45067157304, 126410606437, 355434665605, 1002242216650
|
| gptkbp:status |
approved
|
| gptkbp:title |
Number of rooted trees with n nodes and height at most 2
|
| gptkbp:bfsParent |
gptkb:OEIS_A005195
|
| gptkbp:bfsLayer |
7
|
| https://www.w3.org/2000/01/rdf-schema#label |
OEIS A006005
|