OFFSET
1,1
COMMENTS
Smallest n-digit term of A215420.
EXAMPLE
a(3) = 433 is the smallest 3-digit prime which yields 4 primes by inserting a 7 in every possible position: 7433, 4733, 4373, 4337.
MATHEMATICA
pp[n_, k_] := Catch[Block[{d = IntegerDigits@n}, Do[If[! PrimeQ[ FromDigits[ Insert[d, k, i]]], Throw[False]], {i, 1+Length@d}]; True]]; a[n_] := Catch[ Block[{p = NextPrime[10^(n-1)]}, While[p < 10^n, If[pp[p, 7], Throw@p, p = NextPrime@p]]; 0]]; a /@ Range[8]
CROSSREFS
KEYWORD
nonn,base,more
AUTHOR
Giovanni Resta, Aug 13 2013
STATUS
approved