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Primes with at least one digit appearing exactly five times in the decimal expansion.
2

%I #7 Feb 21 2019 23:15:17

%S 101111,111119,111121,111191,111211,111611,112111,113111,131111,

%T 199999,311111,313333,323333,331333,333233,333323,333331,333337,

%U 333383,333433,333533,334333,343333,353333,444443,444449,511111,555557,599999,611111

%N Primes with at least one digit appearing exactly five times in the decimal expansion.

%C The sequence is probably infinite.

%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 100000 do p := ithprime(n) ; if isdgctm(p,5) then printf("%d,",p) ; fi; od: # _R. J. Mathar_, Jun 21 2009

%Y Cf. A105992, A161786.

%K nonn,base

%O 1,1

%A _Ki Punches_, Jun 19 2009

%E Edited and corrected by _R. J. Mathar_, Jun 21 2009