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A057877
a(n) = smallest n-digit prime in A057876.
2
23, 113, 1531, 12239, 111317, 1111219, 11119291, 111111197, 1111113173, 11111133017, 111111189919, 1111111411337, 11111111161177, 111111111263311, 1111111111149119, 11111111111179913, 111111111111118771, 1111111111111751371, 11111111111111111131, 111111111111113129773, 1111111111111111337111
OFFSET
2,1
EXAMPLE
1531 gives primes 53, 131 and 151 after dropping digits 1, 5 and 3.
MAPLE
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:
Res; # Robert Israel, Jul 13 2018
MATHEMATICA
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}]
KEYWORD
base,nonn
AUTHOR
Patrick De Geest, Oct 15 2000
EXTENSIONS
Extended by Robert G. Wilson v, Dec 17 2002
More terms from Robert Israel, Jul 13 2018
STATUS
approved