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Search: id:A121368
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| A121368 |
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a(1) = a(2) = 1, a(n) = A007947(a(n-1)) + a(n-2), for n >= 3, i.e. a(n)=a(n-2) plus the largest squarefree divisor of a(n-1). |
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3
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| 1, 1, 2, 3, 5, 8, 7, 15, 22, 37, 59, 96, 65, 161, 226, 387, 355, 742, 1097, 1839, 2936, 2573, 5509, 8082, 8203, 16285, 24488, 22407, 46895, 69302, 116197, 185499, 178030, 363529, 541559, 905088, 555701, 1460789, 591330, 2052119, 2643449, 4695568
(list; graph; listen)
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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) = 96. So a(13) = 6 + a(11) = 65.
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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))+a(n-2) fi end: seq(a(n), n=1..25); - Emeric Deutsch (deutsch(AT)duke.poly.edu), Jul 24 2006
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CROSSREFS
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Cf. A007947, A121367, A121369.
Sequence in context: A125727 A112337 A141804 this_sequence A010073 A126167 A026260
Adjacent sequences: A121365 A121366 A121367 this_sequence A121369 A121370 A121371
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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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