%I
%S 10111,11113,11117,11119,11131,11161,11171,11311,11411,16111,22229,
%T 23333,31333,33331,33343,33353,33533,38333,44449,47777,49999,59999,
%U 67777,71777,76777,77377,77477,77747,77773,77797,77977,79777,79999,88883,94999,97777
%N Primes with at least one digit appearing exactly four times in the decimal expansion.
%C The sequence is probably infinite.
%H Harvey P. Dale, <a href="/A161786/b161786.txt">Table of n, a(n) for n = 1..2000</a>
%e 101117 has exactly four 1s.
%p isdgctm := proc(n,d) local dgs,a,i ; dgs := convert(n,base,10) ; a := [seq(0,j=0..9)] ;
%p for i in dgs do a := subsop(i+1=op(i+1,a)+1,a) ; od: if convert(a,set) intersect {d} <> {} then true; else false; fi; end:
%p for n from 1 to 10000 do p := ithprime(n) ; if isdgctm(p,4) then printf("%d,",p) ; fi; od: # R. J. Mathar, Jun 21 2009
%t Select[Prime[Range[186,10000]],MemberQ[DigitCount[#],4]&] (* _Harvey P. Dale_, Apr 12 2015 *)
%K nonn,base
%O 1,1
%A _Ki Punches_, Jun 19 2009
%E Edited and corrected by _R. J. Mathar_, Jun 21 2009
