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A003007 Number of n-level ladder expressions with A002193.
(Formerly M1145)
1
1, 1, 2, 4, 8, 17, 38, 89, 208 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

REFERENCES

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Table of n, a(n) for n=1..9.

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)

Index entries for sequences related to parenthesizing

CROSSREFS

Cf. A003008.

Sequence in context: A006461 A257300 A229202 * A086615 A081124 A090901

Adjacent sequences:  A003004 A003005 A003006 * A003008 A003009 A003010

KEYWORD

nonn,more

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified February 25 22:18 EST 2018. Contains 299662 sequences. (Running on oeis4.)