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Search: id:A121369
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| A121369 |
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a(1) = a(2) = 1, a(n) = A007947(a(n-1))+A007947(a(n-2)) for n >= 3, i.e. a(n)=the largest squarefree divisor of a(n-1) plus the largest squarefree divisor of a(n-2). |
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3
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| 1, 1, 2, 3, 5, 8, 7, 9, 10, 13, 23, 36, 29, 35, 64, 37, 39, 76, 77, 115, 192, 121, 17, 28, 31, 45, 46, 61, 107, 168, 149, 191, 340, 361, 189, 40, 31, 41, 72, 47, 53, 100, 63, 31, 52, 57, 83, 140, 153, 121, 62, 73, 135, 88, 37, 59, 96, 65, 71, 136, 105, 139, 244, 261, 209, 296
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OFFSET
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1,3
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EXAMPLE
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6 is the largest squarefree divisor of a(12) = 36. 29 is the largest squarefree divisor of a(13) = 29. So a(14) = 6 + 29 = 35.
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MAPLE
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with(numtheory): A007947:= proc(n) local i, t1, t2; t1 := ifactors(n)[2]; t2 := mul(t1[i][1], i=1..nops(t1)); end: a:=proc(n) if n=1 or n=2 then 1 else A007947(a(n-1))+A007947(a(n-2)) fi end: seq(a(n), n=1..20); - Emeric Deutsch (deutsch(AT)duke.poly.edu), Jul 24 2006
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CROSSREFS
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Cf. A007947, A121367, A121368.
Adjacent sequences: A121366 A121367 A121368 this_sequence A121370 A121371 A121372
Sequence in context: A010074 A116918 A116917 this_sequence A125727 A112337 A121368
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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), Jul 23 2006
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EXTENSIONS
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More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Jul 24 2006
More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 18 2007
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