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A071997 a(n) is the smallest positive integer that cannot be obtained by using the number 2 at most n times and the operators +, -, *, /. 0
1, 3, 5, 7, 11, 19, 27, 43, 75, 115, 171, 307, 555, 691, 1383, 2467, 3627 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..17.

G. Bannay, LE COMPTE EST BON

EXAMPLE

a(3)=5 because using 2 at most thrice we can get 2/2=1, 2=2, 2+(2/2)=3, 2+2=4, but we cannot obtain 5 in the same way.

CROSSREFS

Sequence in context: A144427 A082603 A161420 * A093442 A155008 A175196

Adjacent sequences:  A071994 A071995 A071996 * A071998 A071999 A072000

KEYWORD

hard,more,nonn

AUTHOR

Koksal Karakus (karakusk(AT)hotmail.com), Jun 17 2002

STATUS

approved

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Last modified August 8 05:50 EDT 2020. Contains 336290 sequences. (Running on oeis4.)