

A077477


Least positive integers not excluded by the rule that if n is present then 2n+1 and 3n+1 are not allowed.


6



1, 2, 6, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 27, 30, 32, 35, 36, 38, 39, 40, 42, 44, 47, 48, 50, 51, 52, 54, 56, 57, 58, 59, 60, 62, 63, 64, 66, 68, 69, 70, 72, 74, 75, 76, 78, 80, 83, 84, 86, 87, 88, 90, 92, 93, 94, 96
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OFFSET

1,2


COMMENTS

What is the limit of a(n)/n?


LINKS



EXAMPLE

a(5)=9 since 9 is not equal to 2*a(k)+1 nor 3*a(k)+1 for 1<=k<5; and since 9 is allowed to be present, then 19(=2*9+1) and 28(=3*9+1) are to be excluded.


MATHEMATICA

s = {1}; Do[u = Union[s, 2s + 1, 3s + 1]; c = Complement[Range[u // Last], u] // First; AppendTo[s, c], {10000}]; s (* JeanFrançois Alcover, Dec 11 2012 *)


PROG

(Haskell)
import Data.List (delete)
a077477 n = a077477_list !! (n1)
a077477_list = f [1..] where
f (x:xs) = x : f (delete (2*x + 1) $ delete (3*x + 1) xs)


CROSSREFS



KEYWORD

easy,nice,nonn


AUTHOR



STATUS

approved



