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 A068958 Smallest value of k such that p | (10^k + 1), where p is the n-th prime; or 0 if no such k exists. 2
 3, 1, 3, 8, 9, 11, 14, 0, 0, 0, 0, 23, 0, 29, 30, 0, 0, 4, 0, 0, 22, 48, 2, 17, 0, 54, 56, 21, 65, 4, 23, 74, 0, 39, 0, 83, 0, 89, 90, 0, 96, 49, 0, 15, 111, 0, 114, 116, 0, 15, 25, 128, 131, 134, 0, 0, 14, 0, 73, 0, 0, 156, 0, 55, 168, 0, 58, 16, 0, 183, 93, 189, 191, 194, 0, 100 (list; graph; refs; listen; history; text; internal format)
 OFFSET 4,1 LINKS Charles R Greathouse IV, Table of n, a(n) for n = 4..10000 EXAMPLE a(4) = 3 as the fourth prime 7 divides 1001. PROG (PARI) a(n)=my(p=prime(n), m=Mod(1, p)); for(k=1, znorder(10*m), if(-1==m*=10, return(k))); 0 \\ Charles R Greathouse IV, Jun 18 2013 CROSSREFS Sequence in context: A188938 A156368 A240665 * A238106 A087000 A289067 Adjacent sequences:  A068955 A068956 A068957 * A068959 A068960 A068961 KEYWORD nonn AUTHOR Amarnath Murthy, Apr 01 2002 EXTENSIONS More terms from Sascha Kurz, Jan 03 2003 STATUS approved

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Last modified May 12 13:02 EDT 2021. Contains 343823 sequences. (Running on oeis4.)