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Search: id:A076530
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| A076530 |
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Numbers n such that sigma(n) = sigma(n+1) - sigma(n-1). |
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+0
1
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| 2, 3, 23, 1967, 3263, 5015, 60455, 1016507, 4420163, 12055511, 14365607, 25726727, 27896423, 66562307, 72764735, 98734967, 175186655, 224868311, 253694927, 288657203, 386668343, 421575407, 504737747, 630645455, 1493547999
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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sigma(24) = 60 sigma(23) = 24 sigma(22) = 36 and 24 = 60 - 36; hence 23 is a term of the sequence.
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MATHEMATICA
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Select[Range[2, 10^5], DivisorSigma[1, # ] == DivisorSigma[1, # + 1] - DivisorSigma[1, # - 1] &]
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CROSSREFS
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Sequence in context: A154553 A160341 A092388 this_sequence A115031 A030418 A037277
Adjacent sequences: A076527 A076528 A076529 this_sequence A076531 A076532 A076533
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KEYWORD
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nonn
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AUTHOR
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Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Oct 18 2002
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EXTENSIONS
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a(8)-a(25) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Feb 01 2009
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