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Search: id:A132274
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| A132274 |
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a(1)=1. a(n+1) = sum{k=1 to n} (kth integer from among those positive integers which are coprime to a(n+1-k)). |
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+0
4
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| 1, 1, 3, 6, 10, 19, 27, 41, 51, 66, 78, 101, 119, 145, 167, 197, 219, 247, 272, 306, 335, 371, 403, 443, 477, 521, 559, 609, 647, 693, 737, 789, 834, 886, 940, 996, 1055, 1118, 1176, 1243, 1306, 1385, 1450, 1523, 1596, 1676, 1749, 1844, 1914, 2010, 2092, 2188
(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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The integers coprime to a(1)=1 are: 1,2,3,4,5,6,... The 5th of these is 5. The integers coprime to a(2)=1 are: 1,2,3,4,5... The 4th of these is 4. The integers coprime to a(3)=3 are: 1,2,4,5,7,... The 3rd of these is 4. The integers coprime to a(4)=6 are: 1,5,7,11,... The 2nd of these is 5. And the integers coprime to a(5)=10 are: 1,3,7,9,11,... The 1st of these is 1. So a(6) = 5 + 4 + 4 + 5 + 1 = 19.
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MAPLE
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A132274 := proc(n) option remember; local a, k, an1k, kcoud, c ; if n = 1 then 1; else a :=0 ; for k from 1 to n-1 do an1k := procname(n-k) ; kcoud := 0 ; for c from 1 do if gcd(c, an1k) = 1 then kcoud := kcoud+1 ; fi; if kcoud = k then a := a+c ; break; fi; od: od: a; fi; end: seq(A132274(n), n=1..60) ; [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jul 20 2009]
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CROSSREFS
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Cf. A132273, A132275.
Sequence in context: A029864 A075111 A080014 this_sequence A091714 A017991 A065614
Adjacent sequences: A132271 A132272 A132273 this_sequence A132275 A132276 A132277
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet Aug 16 2007
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EXTENSIONS
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Extended beyond a(8) by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jul 20 2009
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