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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

Table of n, a(n) for n=1..83.

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.)