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 A089770 Smallest n-digit prime containing no prime substrings, or 0 if no such number exists. 3
 2, 11, 101, 1009, 10009, 100049, 1000081, 10000169, 100000049, 1000000009, 10000000069, 100000000069, 1000000000091, 10000000000099, 100000000000099, 1000000000000091, 10000000000000069, 100000000000000049 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS For n > 1, a(n) ends in 1 or 9 while other digits can be 0,1,4,6,8 or 9. - Robert Israel, Dec 09 2017 LINKS Robert Israel, Table of n, a(n) for n = 1..999 EXAMPLE a(3) = 149 is a term as 1,4,9,14,49 are all nonprimes. 199 is not a member as 19 is a prime. MAPLE N:= 1000: # to get terms until the first where a(n) > 10^(n-1)+10*N+9 filter1:= proc(x)   local k, j;   for k from 0 to ilog10(x) do      for j from k to ilog10(x)+1 do        if isprime(floor((x mod 10^j)/10^k)) then return false fi;   od od:   true end proc: X:= select(filter1, [seq(seq(10*i+j, j=[1, 9]), i=0..N)]): filter2:= proc(p, x)     local k, j;     if not isprime(p) then return false fi;     for k from 1 to ilog10(x)+1 do      if isprime(floor(p /10^k)) then return false fi     od;     true; end proc: for n from 1 do found:= false; for x in X do     p:= 10^(n-1)+x;     if filter2(p, x) then A[n]:= p; found:= true; break fi; od: if not found then break fi od: seq(A[i], i=1..n-1); # Robert Israel, Dec 09 2017 CROSSREFS Cf. A089768, A033274, A089771. Sequence in context: A158578 A003617 A114018 * A249447 A199302 A069663 Adjacent sequences:  A089767 A089768 A089769 * A089771 A089772 A089773 KEYWORD base,nonn AUTHOR Amarnath Murthy, Nov 23 2003 EXTENSIONS Corrected and extended by David Wasserman, Oct 12 2005 STATUS approved

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Last modified April 22 14:27 EDT 2019. Contains 322352 sequences. (Running on oeis4.)