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A161848
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Primes with at least one digit appearing exactly three times in the decimal expansion.
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0
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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
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Sequence is probably infinite.
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EXAMPLE
| 2333, 3313, 3833 all repeat some digit 3 three times.
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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
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CROSSREFS
| Cf.: A161786, A161796
Sequence in context: A151951 A190017 A027622 * A020380 A201034 A145334
Adjacent sequences: A161845 A161846 A161847 * A161849 A161850 A161851
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KEYWORD
| nonn,base
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AUTHOR
| Ki Punches (ki1212(AT)pocketmail.com), Jun 20 2009
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EXTENSIONS
| Edited and corrected by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 21 2009
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