OFFSET
1,1
COMMENTS
By Dirichlet's theorem, there is a prime for each n. For the n in A004023, the smallest prime consists of all ones. - T. D. Noe, Oct 01 2007
LINKS
T. D. Noe, Table of n, a(n) for n=1..200
EXAMPLE
a(4)=23333 because 23333 is the smallest prime ending with exactly 4 identical digits.
MATHEMATICA
sp[n_]:=Module[{k=1}, While[!PrimeQ[k*10^IntegerLength[n]+n], k++]; k*10^IntegerLength[n]+n]; Join[{2, 11}, Table[Min[sp/@FromDigits/@ Table[PadRight[{}, i, n], {n, {1, 3, 7, 9}}]], {i, 3, 20}]] (* Harvey P. Dale, Aug 28 2016 *)
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Shyam Sunder Gupta, Sep 29 2007
STATUS
approved