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Search: id:A128332
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| A128332 |
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a(0)=a(1)=1. For n >= 2, a(n) = number of positive numbers <= n that are coprime to a(n-1)+a(n-2). |
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1
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| 1, 1, 1, 2, 3, 4, 6, 3, 6, 6, 3, 8, 11, 13, 5, 5, 6, 16, 8, 7, 11, 7, 7, 10, 23, 15, 12, 18, 7, 24, 30, 11, 32, 33, 26, 35, 36, 37, 38, 21, 40, 41, 28, 28, 19, 45, 23, 23, 23, 24, 49, 51, 21, 18, 33, 35, 26, 57, 58, 46, 28, 30, 30, 17, 63, 26, 66, 33, 42, 37, 70, 71, 47, 36, 74, 28
(list; graph; listen)
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OFFSET
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0,4
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LINKS
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Leroy Quet, Home Page (listed in lieu of email address)
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EXAMPLE
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a(5)+a(6) = 10. The number of positive integers <= 7 that are coprime to 10 is three, these integers being 1, 3 and 7. So a(7) = 3.
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MAPLE
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a[0]:=1: a[1]:=1: for n from 2 to 100 do ct:=0: for j from 1 to n do if igcd(j, a[n-1]+a[n-2])=1 then ct:=ct+1 else fi od: a[n]:=ct: od: seq(a[n], n=0..100); - Emeric Deutsch (deutsch(AT)duke.poly.edu), May 07 2007
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CROSSREFS
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Sequence in context: A051703 A004567 A030378 this_sequence A074103 A051785 A144825
Adjacent sequences: A128329 A128330 A128331 this_sequence A128333 A128334 A128335
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet May 04 2007
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EXTENSIONS
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More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), May 07 2007
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