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Search: id:A166070
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| A166070 |
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a(0) = 1, for n >= 1, a(n) = numbers k such that sigma(k) is divisible by all proper divisors of k: primes and multiply perfect numbers. |
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3
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| 1, 2, 3, 5, 6, 7, 11, 13, 17, 19, 23, 28, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 120, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Union of primes (A000040) and multiply perfect numbers (A007691). Union of number 1, sequence A053813 and sequence A166069. Union of number 1, primes (A000040), perfect numbers (A000396) and sequence A166069.
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EXAMPLE
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For n = 4 the a(4) = 6, all proper divisors of 6 (1, 2, 3) divides sigma (6) = 12.
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CROSSREFS
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Sequence in context: A062101 A096530 A003174 this_sequence A053813 A116974 A031402
Adjacent sequences: A166067 A166068 A166069 this_sequence A166071 A166072 A166073
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KEYWORD
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nonn,uned
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AUTHOR
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Jaroslav Krizek (jaroslav.krizek(AT)atlas.cz), Oct 06 2009, Oct 16 2009
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