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A075594 a(1) = 1, a(2n) = composite, a(2n+1) = prime and sum of two successive terms is alternately prime or composite. 6
1, 4, 2, 9, 3, 8, 7, 6, 19, 10, 5, 12, 13, 16, 11, 18, 17, 14, 31, 22, 23, 20, 29, 24, 41, 26, 37, 30, 47, 32, 43, 28, 53, 36, 59, 38, 61, 40, 71, 42, 73, 34, 83, 44, 67, 46, 79, 48, 97, 52, 89, 50, 103, 54, 101, 56, 109, 58, 107, 60, 127, 64, 113, 66, 137, 62, 139, 72, 131 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Conjecture: a(n+r)= A075593(n) for n > k for some k and r. What is the value of k and r?

This is not a permutation of the positive integers; odd composites > 9 will not appear in the sequence. - Klaus Brockhaus, Feb 06 2006

LINKS

Table of n, a(n) for n=1..69.

CROSSREFS

Cf. A075593, A103824, A103825.

Sequence in context: A201281 A095303 A060734 * A076022 A064421 A051494

Adjacent sequences:  A075591 A075592 A075593 * A075595 A075596 A075597

KEYWORD

nonn

AUTHOR

Amarnath Murthy, Sep 27 2002

EXTENSIONS

Extended by Ray Chandler Feb 16 2005

STATUS

approved

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Last modified November 20 12:37 EST 2018. Contains 317402 sequences. (Running on oeis4.)