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 A095247 Least k such that concatenation a(1), a(2), a(3), ...a(n-1),a(n) is divisible by n if and only if n is not a prime. 0
 1, 1, 2, 4, 1, 6, 1, 6, 5, 10, 1, 16, 1, 6, 5, 12, 1, 2, 1, 20, 12, 10, 1, 28, 25, 4, 25, 36, 1, 20, 1, 28, 25, 6, 5, 40, 1, 30, 5, 20, 1, 36, 1, 36, 5, 26, 1, 12, 8, 50, 53, 16, 1, 22, 45, 52, 5, 16, 1, 40, 1, 32, 69, 12, 65, 58, 1, 52, 22, 40, 1, 28, 1, 24, 50, 44, 59, 38, 1, 60, 65, 70, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Contribution from Hagen von Eitzen, Oct 03 2009: (Start) a(n) < n + 10^floor(lg(n)). If k >= 1 and n in {10^k, 2*10^k, 5*10^k} then a(n) = n. If n is prime then a(n) in {1, 2}. (End) LINKS EXAMPLE 3 does not divide 112 while 4 divides 1124. CROSSREFS Sequence in context: A125847 A078886 A307796 * A007734 A171233 A096907 Adjacent sequences:  A095244 A095245 A095246 * A095248 A095249 A095250 KEYWORD base,nonn,uned AUTHOR Amarnath Murthy, Jun 17 2004 EXTENSIONS More terms from Hagen von Eitzen, Oct 03 2009 STATUS approved

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Last modified May 23 19:07 EDT 2019. Contains 323528 sequences. (Running on oeis4.)