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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
1, 2, 4, 11, 34, 152, 1143, 8285, 98863, 1211572 (list; graph; refs; listen; history; text; internal format)
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+((34-4)*(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

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Last modified April 20 20:26 EDT 2021. Contains 343137 sequences. (Running on oeis4.)