A131306 Smallest prime ending with exactly n identical digits.

2, 11, 1777, 23333, 199999, 2999999, 19999999, 577777777, 1777777777, 23333333333, 311111111111, 2111111111111, 17777777777777, 499999999999999, 1333333333333333, 23333333333333333

Offset: 1

Author

Shyam Sunder Gupta, Sep 29 2007

Keywords

• base
• nonn

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

Examples

			a(4)=23333 because 23333 is the smallest prime ending with exactly 4 identical digits.
		

Links

• T. D. Noe, Table of n, a(n) for n=1..200

Programs

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 *)