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Search: id:A084891
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| A084891 |
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Multiples of 2, 3, 5, or 7, but not 7-smooth. |
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+0
2
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| 22, 26, 33, 34, 38, 39, 44, 46, 51, 52, 55, 57, 58, 62, 65, 66, 68, 69, 74, 76, 77, 78, 82, 85, 86, 87, 88, 91, 92, 93, 94, 95, 99, 102, 104, 106, 110, 111, 114, 115, 116, 117, 118, 119, 122, 123, 124, 129, 130, 132, 133, 134, 136, 138, 141, 142, 145, 146
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Intersection of A068191 with (A005843, A008585, A008587 and A008589); union of (A005843, A008585, A008587 and A008589) without A002473.
A020639(a(n)) <= 7, A006530(a(n)) > 7.
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LINKS
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Eric Weisstein's World of Mathematics, Smooth Number
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PROGRAM
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Contribution from Cino Hilliard (hillcino368(AT)hotmail.com), Jul 03 2009: (Start)
(PARI) mult2357(m, n) = \\ mult 2, 3, 5, 7 not 7 smooth
{
local(x, a, j, f, ln);
for(x=m, n,
f=0;
if(gcd(x, 210)>1,
a = ifactor(x);
for(j=1, length(a),
if(a[j]>7, f=1; break);
);
if(f, print1(x", "));
);
);
}
ifactor(n) = \\ The vector of the prime factors of n with multiplicity.
{
local(f, j, k, flist);
flist=[];
f=Vec(factor(n));
for(j=1, length(f[1]),
for(k = 1, f[2][j], flist = concat(flist, f[1][j])
);
);
return(flist)
}
(End)
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CROSSREFS
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Sequence in context: A124177 A160078 A066059 this_sequence A162422 A063940 A046442
Adjacent sequences: A084888 A084889 A084890 this_sequence A084892 A084893 A084894
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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), Jul 13 2003
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