A161848 Primes with at least one digit appearing exactly three times in the decimal expansion.

1117, 1151, 1171, 1181, 1511, 1777, 1811, 1999, 2111, 2221, 2333, 2777, 2999, 3313, 3323, 3331, 3343, 3373, 3433, 3533, 3733, 3833, 4111, 4441, 4447, 4999, 5333, 5557, 6661, 7177, 7333, 7477, 7577, 7717, 7727, 7757, 7877, 8111, 8887, 8999, 9199, 9929

Offset: 1

Author

Ki Punches, Jun 20 2009

Keywords

• nonn
• base

Comments

Sequence is probably infinite.

Examples

			2333, 3313, 3833 all repeat some digit 3 three times.
		

Crossrefs

Cf. A161786, A161796.

Programs

Maple

isdgctm := proc(n,d) local dgs,a,i ; dgs := convert(n,base,10) ; a := [seq(0,j=0..9)] ;
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:
for n from 1 to 2000 do p := ithprime(n) ; if isdgctm(p,3) then printf("%d,",p) ; fi; od: # R. J. Mathar, Jun 21 2009

Extensions

Edited and corrected by R. J. Mathar, Jun 21 2009