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Search: id:A070529
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| A070529 |
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Number of divisors of repunit 111...111 (with n digits). |
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+0
3
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| 1, 2, 4, 4, 4, 32, 4, 16, 12, 16, 4, 128, 8, 16, 64, 64, 4, 384, 2, 128, 128, 96, 2, 1024, 32, 64, 64, 256, 32, 8192, 8, 2048, 64, 64, 128, 3072, 8, 8, 64, 2048, 16, 24576, 16, 1536, 768, 64, 4, 8192, 16, 1024, 256, 512, 16, 8192, 256, 4096
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OFFSET
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1,2
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FORMULA
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a(n) =A000005(A002275(n)) =A070528(n)*A051064(n)/(A051064(n)+2)
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EXAMPLE
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a(9)=12 since the divisors of 111111111 are 1, 3, 9, 37, 111, 333, 333667, 1001001, 3003003, 12345679, 37037037, 111111111.
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CROSSREFS
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Sequence in context: A101449 A134188 A140295 this_sequence A009145 A009292 A009622
Adjacent sequences: A070526 A070527 A070528 this_sequence A070530 A070531 A070532
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KEYWORD
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base,nonn
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AUTHOR
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Henry Bottomley (se16(AT)btinternet.com), May 02 2002
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