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Search: id:A108540
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| A108540 |
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Golden semiprimes: a(n)=p*q and abs(p*phi-q)<1, where phi = golden ratio = (1+sqrt(5))/2. |
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+0
16
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| 6, 15, 77, 187, 589, 851, 1363, 2183, 2747, 7303, 10033, 15229, 16463, 17201, 18511, 27641, 35909, 42869, 45257, 53033, 60409, 83309, 93749, 118969, 124373, 129331, 156433, 201563, 217631, 232327, 237077, 255271, 270349, 283663, 303533, 326423
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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a(n) = A108541(n)*A108542(n) = A000040(k)*A108539(k) for some k.
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..1000
Eric Weisstein's World of Mathematics, Golden Ratio
Eric Weisstein's World of Mathematics, Semiprime
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EXAMPLE
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589 = 19*31 and abs(19*phi - 31) = abs(30,7426... - 31) < 1, therefore 589 is a term.
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CROSSREFS
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Cf. A001358, A050508.
Sequence in context: A069750 A035077 A032164 this_sequence A165570 A096565 A013229
Adjacent sequences: A108537 A108538 A108539 this_sequence A108541 A108542 A108543
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KEYWORD
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nonn
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AUTHOR
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Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jun 09 2005; revised Jun 13 2005
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EXTENSIONS
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Corrected by T. D. Noe (noe(AT)sspectra.com), Oct 25 2006
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