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A003007
Number of n-level ladder expressions with A002193.
(Formerly M1145)
2
1, 1, 2, 4, 8, 17, 38, 89, 208
OFFSET
1,3
REFERENCES
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
R. K. Guy and J. L. Selfridge, The nesting and roosting habits of the laddered parenthesis, Amer. Math. Monthly 80 (8) (1973), 868-876.
R. K. Guy and J. L. Selfridge, The nesting and roosting habits of the laddered parenthesis. (annotated cached copy)
CROSSREFS
Cf. A003008.
Sequence in context: A006461 A257300 A229202 * A086615 A357903 A081124
KEYWORD
nonn,more
STATUS
approved