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Search: id:A141059
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| A141059 |
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Number of m such that n=0 Mod UnitarySigma(m). |
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+0
1
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| 1, 1, 2, 2, 2, 3, 1, 3, 3, 3, 1, 6, 1, 2, 3, 3, 2, 6, 1, 6, 2, 1, 1, 10, 2, 2, 3, 4, 1, 8, 1, 5, 3, 2, 2, 11, 1, 2, 2, 8, 1, 6, 1, 3, 4, 1, 1, 13, 1, 5, 3, 3, 1, 9, 2, 6, 2, 1, 1, 17, 1, 2, 3, 5, 3, 4, 1, 5, 2, 5, 1, 21, 1, 2, 3, 3, 1, 5, 1, 11, 3, 2, 1, 13, 3, 1, 2, 4, 1, 15, 1, 2, 2, 1, 2, 19, 1, 3, 4, 9, 1, 6
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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If p is prime but not a Fermat prime then a(p)=1
Least k such that a(k) = n: 1, 3, 6, 28, 32, 12, 112, 30, 54, 24, 36, 126, 48, 200, 90, 160, 60, 264, 96, 400, ..., . - Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 7 2008
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MATHEMATICA
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usigma[n_] := Block[{d = Divisors[n]}, Plus @@ Select[d, GCD[ #, n/# ] == 1 &]]; f[n_] := Block[{c = 0, m = 1}, While[m <= n, If[ Mod[n, usigma@ m] == 0, c++ ]; m++ ]; c]; Array[f, 102] - Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 7 2008
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CROSSREFS
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Cf. A063974.
Sequence in context: A141298 A103960 A024936 this_sequence A135151 A014843 A116987
Adjacent sequences: A141056 A141057 A141058 this_sequence A141060 A141061 A141062
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KEYWORD
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nonn
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AUTHOR
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Yasutoshi Kohmoto, zbi74583.boat(AT)orange.zero.jp, Aug 01 2008
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 7 2008
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