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Search: id:A129141
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| A129141 |
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a(1)=a(2)=1. a(n) = the n-th integer from among those positive integers coprime to (a(n-1)*a(n-2)). |
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+0
2
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| 1, 1, 3, 5, 8, 13, 15, 16, 31, 19, 11, 13, 15, 29, 28, 39, 61, 29, 19, 21, 40, 97, 57, 37, 41, 26, 59, 61, 29, 31, 33, 53, 56, 81, 121, 59, 40, 97, 99, 65, 92, 119, 111, 86, 139, 93, 73, 76, 105, 227, 109, 52, 115, 151, 72, 169, 185, 81, 113, 89, 61, 63, 110, 307, 177, 100
(list; graph; listen)
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OFFSET
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1,3
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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(4)*a(5) = 40. So a(6) = the sixth integer from among those positive integers coprime to 40 (ie, the sixth integer in the sequence 1,3,7,9,11,13,17,19,21,23,...). So a(6) = 13.
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MAPLE
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a[1]:=1: a[2]:=1: for n from 3 to 80 do A:={}: for i from 1 to 500 do if gcd(i, a[n-1]*a[n-2])=1 then A:=A union {i} else fi od: a[n]:=A[n]: od: seq(a[n], n=1..80); - Emeric Deutsch (deutsch(AT)duke.poly.edu), Apr 12 2007
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CROSSREFS
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Cf. A129140.
Adjacent sequences: A129138 A129139 A129140 this_sequence A129142 A129143 A129144
Sequence in context: A147880 A020643 A092360 this_sequence A097431 A123929 A036715
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet Mar 30 2007
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EXTENSIONS
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More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Apr 12 2007
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