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 A138310 a(1)=1. a(n) = smallest positive integer not occurring among the first n-1 terms of the sequence that is coprime to n and is coprime to every (nonzero) exponent in the prime factorization of n. 2
 1, 3, 2, 5, 4, 7, 6, 11, 13, 9, 8, 17, 10, 15, 14, 19, 12, 23, 16, 21, 20, 25, 18, 29, 27, 31, 22, 33, 24, 37, 26, 39, 28, 35, 32, 41, 30, 43, 34, 47, 36, 53, 38, 45, 49, 51, 40, 55, 57, 59, 44, 61, 42, 65, 46, 67, 50, 63, 48, 71, 52, 69, 73, 77, 54, 79, 56, 75, 58, 81, 60, 83 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Table of n, a(n) for n=1..72. EXAMPLE 12 has the prime-factorization of 2^2 * 3^1. The positive integers that don't occur among the first 11 terms of the sequence are 10,12,14,15,16,17,18,19,... Of these integers, 17 is the smallest that is coprime to the exponents in the prime factorization of 12 (i.e., coprime to 2 and 1) and is coprime to 12. So a(12) = 17. CROSSREFS Cf. A138308, A138311. Sequence in context: A353904 A353780 A080261 * A270197 A332769 A191709 Adjacent sequences: A138307 A138308 A138309 * A138311 A138312 A138313 KEYWORD nonn AUTHOR Leroy Quet, Mar 13 2008 EXTENSIONS More terms from Max Alekseyev, Apr 24 2010 STATUS approved

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Last modified September 12 04:22 EDT 2024. Contains 375842 sequences. (Running on oeis4.)