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Search: id:A121367
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| A121367 |
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a(1) = a(2) = 1, a(n) = a(n-1)+A007947(a(n-2)) for n >= 3, i.e. a(n)=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, 13, 15, 28, 43, 57, 100, 157, 167, 324, 491, 497, 988, 1485, 1979, 2144, 4123, 4257, 8380, 9799, 13989, 23788, 37777, 49671, 87448, 104005, 125867, 229872, 355739, 384473, 740212, 1124685, 1494791, 1536446, 3031237, 4567683, 7598920
(list; graph; listen)
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OFFSET
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1,3
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EXAMPLE
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14 is the largest squarefree divisor of a(9) = 28. So a(11) = a(10) + 14 = 57.
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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 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, A121368, A121369.
Sequence in context: A138183 A076591 A078695 this_sequence A070217 A001149 A081612
Adjacent sequences: A121364 A121365 A121366 this_sequence A121368 A121369 A121370
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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 11 2007
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