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A220471 Number of closed simply typable lambda-terms of size n with size 0 for the variables. 0
1, 2, 9, 40, 238, 1564, 11807, 98529, 904318, 9006364 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Typable terms are terms that satisfy constraints which make them well formed.

The current computation requires one to generate all the plain lambda terms and to sieve out those that are typable.  This is feasible for the 63782411 terms of size 10 but not for the 851368766 terms of size 11.

REFERENCES

Alonzo Church, A Formulation of the Simple Theory of Types, J. Symb. Log. 5(2): 56-68 (1940).

LINKS

Table of n, a(n) for n=1..10.

Katarzyna Grygiel and Pierre Lescanne, Counting and generating lambda-terms, arXiv preprint arXiv:1210.2610, 2012

CROSSREFS

Cf. A220894.

Sequence in context: A038156 A052846 A056844 * A213095 A238372 A002825

Adjacent sequences:  A220468 A220469 A220470 * A220472 A220473 A220474

KEYWORD

nonn,more

AUTHOR

Pierre Lescanne, Apr 10 2013

STATUS

approved

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Last modified April 17 03:18 EDT 2014. Contains 240628 sequences.