

A093679


Sequence contains no 3term arithmetic progression, starting with 1,10.


7



1, 10, 11, 13, 14, 20, 22, 23, 28, 37, 38, 40, 41, 47, 49, 50, 82, 91, 92, 94, 95, 101, 103, 104, 109, 118, 119, 121, 122, 128, 130, 131, 244, 253, 254, 256, 257, 263, 265, 266, 271, 280, 281, 283, 284, 290, 292, 293, 325, 334, 335, 337, 338, 344, 346, 347
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OFFSET

1,2


COMMENTS

a(1)=1, a(2)=10; a(n) is least k such that no three terms of a(1),a(2),...,a(n1),k form an arithmetic progression.


LINKS

Table of n, a(n) for n=1..56.
Index entries related to nonaveraging sequences


FORMULA

a(n) = sum[k=1, n1, (3^A007814(k)+1)/2] + f(n), with f(n) an 8periodic function with values {1, 9, 8, 9, 5, 10, 10, 10, ...}, n>=1, as proved by Lawrence Sze.


CROSSREFS

Cf. A004793, A033157, A093678A093681, A092482.
Row 4 of array in A093682.
Sequence in context: A047791 A253610 A302578 * A153194 A175224 A106439
Adjacent sequences: A093676 A093677 A093678 * A093680 A093681 A093682


KEYWORD

nonn


AUTHOR

Ralf Stephan, Apr 09 2004


STATUS

approved



