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A057877
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a(n) = smallest n-digit prime in A057876.
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2
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23, 113, 1531, 12239, 111317, 1111219, 11119291, 111111197, 1111113173, 11111133017, 111111189919, 1111111411337, 11111111161177, 111111111263311, 1111111111149119, 11111111111179913, 111111111111118771, 1111111111111751371, 11111111111111111131, 111111111111113129773, 1111111111111111337111
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OFFSET
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2,1
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LINKS
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EXAMPLE
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1531 gives primes 53, 131 and 151 after dropping digits 1, 5 and 3.
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MAPLE
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filter:= proc(n) local L, d, Lp;
if not isprime(n) then return false fi;
L:= convert(n, base, 10);
for d in convert(L, set) do
Lp:= subs(d=NULL, L);
if Lp=[] or Lp[-1] = 0 then return false fi;
if not isprime(add(Lp[i]*10^(i-1), i=1..nops(Lp))) then return false fi;
od;
true
end proc:
Res:= NULL:
for t from 1 to 21 do
for x from (10^(t+1)-1)/9 by 2 do
if filter(x) then Res:= Res, x; break fi
od
od:
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MATHEMATICA
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Do[k = (10^n - 1)/9; While[d = IntegerDigits[k]; !PrimeQ[k] || !PrimeQ[ FromDigits[ DeleteCases[d, 0]]] || !PrimeQ[ FromDigits[ DeleteCases[d, 1]]] || !PrimeQ[ FromDigits[ DeleteCases[d, 2]]] || !PrimeQ[ FromDigits[ DeleteCases[d, 3]]] || !PrimeQ[ FromDigits[ DeleteCases[d, 4]]] || !PrimeQ[ FromDigits[ DeleteCases[d, 5]]] || !PrimeQ[ FromDigits[ DeleteCases[d, 6]]] || !PrimeQ[ FromDigits[ DeleteCases[d, 7]]] || !PrimeQ[ FromDigits[ DeleteCases[d, 8]]] || !PrimeQ[ FromDigits[ DeleteCases[d, 9]]], k++ ]; Print[k], {n, 2, 19}]
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CROSSREFS
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Cf. A057876, A057877, A057878, A057879, A057880, A057881, A057882, A057883, A051362, A034302, A034303, A034304, A034305.
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KEYWORD
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base,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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