

A217043


a(1) = 1; a(n+1) is the smallest integer >=0 that cannot be obtained from the integers {a(1), ..., a(n)} using each number at most once and the operators +, , *, / and accepting fractional intermediate results.


0




OFFSET

1,2


LINKS

Table of n, a(n) for n=1..10.
G. Bannay, Le Compte Est Bon


EXAMPLE

a(4)=11 because we can write 4+1=5, 4+2=6, 4+2+1=7, 4*2=8, 4*2+1=9, (4+1)*2=10 by using 1, 2 and 4, but we cannot construct 11 this way.
a(7)=1143 because 1142 = (152+((344)*(11*(2+1)))), and 1143 is impossible.
a(7) is not 1007 because it can be constructed as 1007 = 152*(11(34+1)/(4*2)); the fractional intermediate result 35/8, for example, is accepted in the composition.


CROSSREFS

Cf. A071115 (disallows intermediate fractions).
Sequence in context: A289588 A238425 A071115 * A249696 A156809 A215620
Adjacent sequences: A217040 A217041 A217042 * A217044 A217045 A217046


KEYWORD

nonn,more


AUTHOR

Clément Morelle, Sep 25 2012


STATUS

approved



