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Search: id:A080193
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| A080193 |
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5-smooth numbers which are not 3-smooth. |
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+0
3
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| 5, 10, 15, 20, 25, 30, 40, 45, 50, 60, 75, 80, 90, 100, 120, 125, 135, 150, 160, 180, 200, 225, 240, 250, 270, 300, 320, 360, 375, 400, 405, 450, 480, 500, 540, 600, 625, 640, 675, 720, 750, 800, 810, 900, 960, 1000, 1080, 1125, 1200, 1215, 1250, 1280, 1350
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Numbers of the form 2^r*3^s*5^t with r, s >= 0, t > 0.
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EXAMPLE
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15 = 3*5 is a term but 18 = 2*3^2 is not.
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PROGRAM
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(PARI) {m=1440; z=[]; for(r=0, floor(log(m)/log(2)), a=2^r; for(s=0, floor(log(m/a)/log(3)), b=a*3^s; for(t=1, floor(log(m/b)/log(5)), z=concat(z, b*5^t)))); z=vecsort(z); for(i=1, length(z), print1(z[i], ", "))}
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CROSSREFS
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Cf. A051037, A003586.
Sequence in context: A061821 A085128 A067761 this_sequence A023722 A043349 A028435
Adjacent sequences: A080190 A080191 A080192 this_sequence A080194 A080195 A080196
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KEYWORD
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easy,nonn
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AUTHOR
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Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Feb 10 2003
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