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 A130024 a(1)=1. a(n) = number of earlier terms which don't have 2 or more distinct prime divisors in common with n. 0
 1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10, 12, 13, 14, 15, 16, 15, 18, 17, 20, 21, 22, 20, 24, 25, 26, 26, 28, 19, 30, 31, 32, 33, 34, 30, 36, 37, 38, 33, 40, 31, 42, 42, 40, 45, 46, 38, 48, 41, 50, 49, 52, 43, 54, 51, 56, 57, 58, 38, 60, 61, 59, 63, 64, 50, 66, 66, 68, 53, 70, 57, 72 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS EXAMPLE The distinct primes which divide 20 are 2 and 5. So a(20) is the number of earlier terms which are not divisible by at least 2 distinct primes dividing 20; i.e. are not divisible by both 2 and 5. Among the first 19 terms only a(11)=10 and a(12)=10 are divisible by both 2 and 5. There are 17 other earlier terms, so a(20)=17. CROSSREFS Cf. A131232. Sequence in context: A122262 A172268 A017895 * A131232 A010881 A190600 Adjacent sequences:  A130021 A130022 A130023 * A130025 A130026 A130027 KEYWORD nonn AUTHOR Leroy Quet Jun 20 2007 EXTENSIONS More terms from Joshua Zucker, Jul 18 2007 STATUS approved

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Last modified May 21 02:50 EDT 2013. Contains 225474 sequences.