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Search: id:A138308
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| A138308 |
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a(1)=1. a(n) = smallest integer > a(n-1) that is coprime to n and is coprime to every (nonzero) exponent in the prime factorization of n. |
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3
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| 1, 3, 4, 5, 6, 7, 8, 11, 13, 17, 18, 19, 20, 23, 26, 27, 28, 29, 30, 31, 32, 35, 36, 37, 39, 41, 43, 45, 46, 47, 48, 49, 50, 53, 54, 55, 56, 59, 61, 67, 68, 71, 72, 73, 77, 79, 80, 83, 85, 87, 88, 89, 90, 91, 92, 95, 97, 99, 100, 101, 102, 103, 107, 109, 111, 113, 114, 115, 116
(list; graph; listen)
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OFFSET
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1,2
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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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8 has the prime-factorization of 2^3. The smallest integer > a(7)=8 that is coprime to both 8 and 3 is 11. (9 is not coprime to 3. 10 is not coprime to 8.) So a(8)=11.
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MAPLE
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A138308 := proc(n) option remember; local pfs, a, p, works ; if n = 1 then 1; else pfs := ifactors(n)[2] ; for a from procname(n-1)+1 do works := true ; if gcd(a, n) > 1 then works := false; else for p in pfs do if gcd(a, op(2, p)) > 1 then works := false; fi; end do ; end if; if works then return a; end if ; end do; end if; end: seq(A138308(n), n=1..120) ; [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 24 2009]
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CROSSREFS
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Cf. A138309, A138310.
Sequence in context: A120561 A051016 A044951 this_sequence A039084 A085627 A057825
Adjacent sequences: A138305 A138306 A138307 this_sequence A138309 A138310 A138311
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet Mar 13 2008
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EXTENSIONS
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Extended beyond a(14) by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 24 2009
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