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A105266 a(1)=1 and, for n>1, a(n) is the smallest integer greater than a(n-1) such that no three terms x,y,z of the sequence, with x<y<z, satisfy z-y=y-x+1. 0
1, 2, 3, 7, 8, 9, 19, 20, 21, 25, 26, 27, 55, 56, 57, 61, 62, 63, 73, 74, 75, 79, 80, 81, 163, 164, 165, 169, 170, 171, 181, 182, 183, 187, 188, 189, 217, 218, 219, 223, 224, 225, 235, 236, 237, 241, 242, 243, 487, 488, 489, 493, 494, 495, 505, 506, 507, 511, 512 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

It appears that {a(n)] consists exactly of those positive integers whose base-3 representation satisfies (i) only 0's follow a 1 and (ii) a final run of 0's must follow a 1.

LINKS

Table of n, a(n) for n=1..59.

CROSSREFS

Cf. A003278.

Sequence in context: A246440 A332699 A347153 * A246448 A054996 A338691

Adjacent sequences:  A105263 A105264 A105265 * A105267 A105268 A105269

KEYWORD

nonn

AUTHOR

John W. Layman, Apr 15 2005

STATUS

approved

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Last modified September 21 21:32 EDT 2021. Contains 347605 sequences. (Running on oeis4.)