OEIS A006005

GPTKB entity

Statements (25)
Predicate Object
gptkbp:instanceOf 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 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
https://www.w3.org/2000/01/rdf-schema#label OEIS 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