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A229072
Lexicographically earliest sequence of distinct natural numbers such that, for any number n in the sequence, the positions of the 1's in the binary representation of n are in the sequence, whereas the positions of the 0's are not.
1
1, 4, 9, 18, 36, 72, 144, 289, 578, 1156, 2312, 4624, 9248, 18496, 36992, 73984, 147969, 295938, 591876, 1183752, 2367504, 4735008, 9470016, 18940032, 37880064, 75760128, 151520256, 303040512, 606081024, 1212162048, 2424324096, 4848648192, 9697296384
OFFSET
1,2
COMMENTS
The position 1 corresponds to the most significant bit.
FORMULA
a(n) = Sum_{a(i) <= n+1} 2^(n+1-a(i)), for any n>1, with a(1)=1.
EXAMPLE
1 has a 1 at position 1, and no 0's, hence 1 belongs to the sequence.
2 has a 0 at position 2, hence 2 cannot belong to the sequence.
3 has a 1 at position 2, as 2 cannot belong to the sequence, 3 cannot either.
4 has a 1 at position 1, and 0's at positions 2 and 3, hence 4 belongs to the sequence.
9 has 1's at positions 1 and 4, and 0's at positions 2 and 3, hence 9 belongs to the sequence.
PROG
(PARI) See Link section.
CROSSREFS
Cf. A098645.
Sequence in context: A122039 A083706 A352667 * A261983 A074896 A015713
KEYWORD
nonn,base
AUTHOR
Paul Tek, Sep 12 2013
STATUS
approved