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Search: id:A139082
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| A139082 |
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a(n) = (largest power of a prime dividing n) * (largest power of a prime dividing (n+1)). |
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+0
3
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| 2, 6, 12, 20, 15, 21, 56, 72, 45, 55, 44, 52, 91, 35, 80, 272, 153, 171, 95, 35, 77, 253, 184, 200, 325, 351, 189, 203, 145, 155, 992, 352, 187, 119, 63, 333, 703, 247, 104, 328, 287, 301, 473, 99, 207, 1081, 752, 784, 1225, 425, 221, 689, 1431, 297, 88, 152, 551
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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The largest prime-power dividing 12 is 4. The largest prime power dividing 13 is 13. So a(12) = 4*13 = 52.
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FORMULA
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a(n)=A034699(n)*A034699(n+1). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 16 2008
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MAPLE
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isA000961 := proc(n) if nops(ifactors(n)[2]) =1 then true ; else false ; fi ; end: A034699 := proc(n) local dvs, d ; if n = 1 then RETURN(1) ; fi ; dvs := sort(convert(numtheory[divisors](n), list), `>`) ; for d in dvs do if isA000961(d) then RETURN(d) ; fi ; od: RETURN(0) ; end: A139082 := proc(n) A034699(n)*A034699(n+1) ; end: seq(A139082(n), n=1..100) ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 16 2008
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CROSSREFS
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Cf. A139081, A139084.
Sequence in context: A139084 A086958 A130492 this_sequence A061078 A067114 A102711
Adjacent sequences: A139079 A139080 A139081 this_sequence A139083 A139084 A139085
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), Apr 07 2008
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EXTENSIONS
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More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 16 2008
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