

A092482


Sequence contains no 3term arithmetic progression, other than its initial terms 1,2,3.


12



1, 2, 3, 6, 7, 14, 15, 17, 18, 36, 37, 39, 40, 45, 46, 48, 49, 98, 99, 101, 102, 107, 108, 110, 111, 125, 126, 128, 129, 134, 135, 137, 138, 276, 277, 279, 280, 285, 286, 288, 289, 303, 304, 306, 307, 312, 313, 315, 316, 357, 358, 360, 361, 366, 367, 369, 370
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OFFSET

1,2


COMMENTS

a(1)=1, a(2)=2, a(3)=3; a(n) is least k such that no three terms of a(1), a(2), ..., a(n1), k form an arithmetic progression, except for the first triple (1,2,3).


LINKS

Table of n, a(n) for n=1..57.
Eric Weisstein's World of Mathematics, Nonarithmetic Progression Sequence.
Index entries related to nonaveraging sequences


FORMULA

For n>2, a(n+2) = 1 + 2^[log2(n)] + sum[k=1, n, (3^A007814(n)+1)/2] = 1 + A053644(n) + A005836(n) (conjectured and checked up to n=512).


CROSSREFS

Cf. A004793, A033157.
Sequence in context: A233423 A256800 A172105 * A147303 A075427 A066880
Adjacent sequences: A092479 A092480 A092481 * A092483 A092484 A092485


KEYWORD

nonn


AUTHOR

Ralf Stephan, Apr 04 2004


EXTENSIONS

Name clarified by Charles R Greathouse IV, Jan 30 2014


STATUS

approved



