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Search: id:A130882
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| 0, 4, 7, 2, 4, 5, 13, 2, 7, 4, 19, 2, 4, 23, 2, 5, 2, 13, 4, 31, 2, 3, 2, 17, 37, 2, 19, 4, 43, 2, 4, 47, 2, 7, 2, 5, 53, 2, 5, 2, 4, 29, 61, 2, 3, 2, 4, 67, 2, 4, 5, 73, 2, 3, 2, 4, 79, 2, 4, 83, 2, 5, 2, 43, 89, 2, 7, 2, 3, 2, 47, 97
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OFFSET
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1,2
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COMMENT
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a(n) is the weight of composite numbers. A020639(n) is the weight of natural numbers. A117078(n) is the weight of primes numbers.
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LINKS
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Remi Eismann, Table of n, a(n) for n=1..9999
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EXAMPLE
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For n = 1 we have A002808(n) = 4, A002808(n+1) = 6; there is no k such that 6 - 4 = 2 = (4 mod k), hence a(1) = 0.
For n = 3 we have A002808(n) = 8, A002808(n+1) = 9; 7 is the smallest k such that 9 - 8 = 1 = (8 mod k), hence a(3) = 7.
For n = 24 we have A002808(n) = 36, A002808(n+1) = 38; 17 is the smallest k such that 38 - 36 = 2 = (36 mod k), hence a(24) = 17.
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CROSSREFS
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Cf. A020639, A117078, A117563, A001223, A118534, A090369, A090368, A130533, A130650, A130703.
Sequence in context: A133390 A011351 A132026 this_sequence A113963 A071932 A139348
Adjacent sequences: A130879 A130880 A130881 this_sequence A130883 A130884 A130885
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KEYWORD
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nonn
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AUTHOR
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Remi Eismann (reismann(AT)free.fr), Aug 21 2007
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