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A101267 a(1) = 1; a(n) = a(2^ceiling(log_2(n))+1-n)th smallest positive integer not yet in the sequence. +0
2
1, 2, 4, 3, 7, 9, 6, 5, 13, 15, 19, 17, 11, 14, 10, 8, 24, 27, 32, 29, 37, 40, 35, 33, 21, 23, 30, 26, 18, 22, 16, 12, 44, 49, 56, 52, 62, 67, 59, 57, 73, 76, 82, 79, 69, 74, 66, 63, 39, 43, 50, 46, 58, 64, 54, 51, 34, 38, 47, 42, 28, 36, 25, 20, 84, 90, 102, 94, 110, 116, 106 (list; graph; listen)
OFFSET

1,2

COMMENT

Sequence is a permutation of the positive integers. 2^ceiling(log_2(n)) +1 -n is sequence A080079 with a change of offset.

EXAMPLE

Since 2^ceiling(log_2(n)) +1 -n = 3 at n = 6, a(6) = the a(3)th (the 4th) smallest positive integer not among the first 5 terms of the sequence. The positive integers not among the first 5 terms are 5,6,8,9,10,... The 4th of these is 9, which is a(6).

MATHEMATICA

a[1] = 1; a[n_] := a[n] = Complement[ Range[100], Table[ a[i], {i, n - 1}]] [[ a[2^Ceiling[ Log[2, n]] + 1 - n]]]; Table[ a[n], {n, 71}] (from Robert G. Wilson v Jan 13 2005)

CROSSREFS

Sequence in context: A026167 A127002 A027634 this_sequence A090568 A035507 A138612

Adjacent sequences: A101264 A101265 A101266 this_sequence A101268 A101269 A101270

KEYWORD

easy,nonn

AUTHOR

Leroy Quet (q1qq2qqq3qqqq(AT)yahoo.com), Dec 18 2004

EXTENSIONS

More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 13 2005

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Last modified November 30 22:12 EST 2008. Contains 150989 sequences.


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