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Search: id:A098709
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| A098709 |
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a(n) = smallest positive multiple of (number of terms of {a(1),a(2),..a(n-1)} which are coprime to n) which is not among previous terms of sequence. |
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+0
1
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| 1, 2, 4, 3, 8, 5, 6, 9, 10, 12, 20, 14, 24, 16, 18, 28, 32, 22, 36, 15, 30, 25, 44, 21, 54, 7, 45, 35, 56, 26, 60, 40, 17, 50, 72, 42, 108, 11, 63, 48, 80, 55, 84, 96, 75, 90, 46, 64, 39, 27, 100, 112, 52, 88, 34, 13, 128, 126, 58, 65, 120, 19, 150, 140, 160, 81, 66, 180, 37
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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This sequence does not include all positive integers; the first few omitted values are 73,163,177,197,229. At n=931, the number of non-composite values in the sequence exceeds 77 and numbers in this range can be divisible by at most 4 distinct primes, so any value from that point on must exceed 73. (This is not quite a proof; there could stop being any prime values in the sequence until p_k primorial catches up with the difference; but it is obvious that this does not happen.) - Frank Adams-Watters (FrankTAW(AT)Netscape.net), Jun 02 2006
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LINKS
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Leroy Quet, Home Page (listed in lieu of email address)
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EXAMPLE
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a(8) is 9 because there are 3 terms of the sequence among the first 7 terms which are coprime to 8 and 9 is the smallest positive multiple of 3 not among the first 7 terms of the sequence.
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CROSSREFS
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Sequence in context: A057495 A048167 A135141 this_sequence A054238 A048679 A075378
Adjacent sequences: A098706 A098707 A098708 this_sequence A098710 A098711 A098712
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet Sep 28 2004
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EXTENSIONS
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More terms from Frank Adams-Watters (FrankTAW(AT)Netscape.net), Jun 02 2006
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