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Search: id:A133580
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| A133580 |
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a(0)=a(1)=1; for n>1, a(n) = 2*a(n-1) + 1 if a(n-1) and n are coprime, otherwise a(n) = a(n-1)/gcd(a(n-1),n). |
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+0
1
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| 1, 1, 3, 1, 3, 7, 15, 31, 63, 7, 15, 31, 63, 127, 255, 17, 35, 71, 143, 287, 575, 1151, 2303, 4607, 9215, 1843, 3687, 1229, 2459, 4919, 9839, 19679, 39359, 78719, 157439, 314879, 629759, 1259519, 2519039, 5038079, 10076159, 20152319, 40304639
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OFFSET
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1,3
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MATHEMATICA
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a = {1, 1}; Do[If[GCD[n, a[[ -1]]] == 1, b = 2*a[[ -1]] + 1, b = a[[ -1]]/GCD[a[[ -1]], n]]; AppendTo[a, b], {n, 2, 50}]; a - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Dec 31 2007
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CROSSREFS
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Sequence in context: A095732 A001644 A139123 this_sequence A019603 A132476 A103279
Adjacent sequences: A133577 A133578 A133579 this_sequence A133581 A133582 A133583
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KEYWORD
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nonn
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AUTHOR
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Ctibor O. ZIZKA (ctibor.zizka(AT)seznam.cz), Dec 26 2007
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EXTENSIONS
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Corrected and extended by Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Dec 31 2007
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