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Search: id:A080684
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| A080684 |
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Number of 13-smooth numbers <= n. |
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+0
1
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| 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 16, 17, 17, 18, 19, 20, 20, 21, 22, 23, 24, 25, 25, 26, 26, 27, 28, 28, 29, 30, 30, 30, 31, 32, 32, 33, 33, 34, 35, 35, 35, 36, 37, 38, 38, 39, 39, 40, 41, 42, 42, 42, 42, 43, 43, 43, 44, 45, 46, 47, 47, 47, 47, 48, 48, 49
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Range = primes 2 to 13. Input pn=13 in script below. Code below is much faster than the code for cross-reference. For input of n=200 13 times as fast and many times faster for larger input of n.
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PROGRAM
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(PARI) smoothn(n, pn) = { for(m=1, n, pr=1; forprime(p=2, pn, pr*=p; ); ct=1; for(x=1, m, f=0; forprime(y=nextprime(pn+1), floor(x), if(x%y == 0, f=1; break) ); if(gcd(x, pr)<>1, if(f==0, ct+=1; )) ); print1(ct", "); ) }
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CROSSREFS
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Cf. A071520, A051038.
Sequence in context: A057946 A117657 A106618 this_sequence A159062 A093616 A089247
Adjacent sequences: A080681 A080682 A080683 this_sequence A080685 A080686 A080687
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KEYWORD
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easy,nonn
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AUTHOR
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Cino Hilliard (hillcino368(AT)gmail.com), Mar 02 2003
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