A093679 - OEIS

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A093679

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

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(n-1), k form an arithmetic progression.

LINKS

Table of n, a(n) for n=1..56.

Index entries related to non-averaging sequences

FORMULA

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

CROSSREFS

Cf. A004793, A033157, A093678, A093680, A093681, 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