This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A241027 Smallest prime numbers p of length n having a decimal expansion x(1)x(2)... x(n) such that there exists an index j where x(j) = 1 and x(i) = 7 for i<>j, or 0 if no such prime exists. 2
 17, 0, 1777, 71777, 0, 0, 77777177, 0, 1777777777, 71777777777, 0, 7177777777777, 17777777777777, 0, 7717777777777777, 0, 0, 7777177777777777777, 71777777777777777777, 0, 7777717777777777777777, 77717777777777777777777, 0, 7777771777777777777777777 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,1 COMMENTS The corresponding index of the decimal digit 1 are 1, 0, 1, 2, 0, 0, 6, 0, 1, 2, 0, 2, 1, 0, 3, 0, 0, 5, 2,...(A241020). LINKS Michel Lagneau, Table of n, a(n) for n = 2..150 MAPLE with(numtheory):nn:=80:T:=array(1..nn):    for n from 2 to nn do:      for i from 1 to n do:      T[i]:=7:      od:        ii:=0:        for j from 1 to n while(ii=0)do:        T[j]:=1:s:=sum('T[i]*10^(n-i)', 'i'=1..n):          if type(s, prime)=true          then          ii:=1: printf(`%d, `, s):          else          T[j]:=7:          fi:        od:           if ii=0            then            printf(`%d, `, 0):            else           fi:      od: CROSSREFS Cf. A241018, A241019, A241020, A241022. Sequence in context: A198631 A185685 A144692 * A176728 A300909 A088469 Adjacent sequences:  A241024 A241025 A241026 * A241028 A241029 A241030 KEYWORD nonn,base AUTHOR Michel Lagneau, Apr 15 2014 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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified November 18 07:01 EST 2018. Contains 317279 sequences. (Running on oeis4.)