This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A131306 Smallest prime ending with exactly n identical digits. 1
 2, 11, 1777, 23333, 199999, 2999999, 19999999, 577777777, 1777777777, 23333333333, 311111111111, 2111111111111, 17777777777777, 499999999999999, 1333333333333333, 23333333333333333 (list; graph; refs; listen; history; text; internal format)
 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 Sequence in context: A051254 A095820 A101295 * A145797 A284739 A246518 Adjacent sequences:  A131303 A131304 A131305 * A131307 A131308 A131309 KEYWORD base,nonn AUTHOR Shyam Sunder Gupta, Sep 29 2007 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified June 18 14:52 EDT 2019. Contains 324213 sequences. (Running on oeis4.)