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Search: id:A161786
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| A161786 |
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Primes with at least one digit appearing exactly four times in the decimal expansion. |
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+0
4
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| 10111, 11113, 11117, 11119, 11131, 11161, 11171, 11311, 11411, 16111, 22229, 23333, 31333, 33331, 33343, 33353, 33533, 38333, 44449, 47777, 49999, 59999, 67777, 71777, 76777, 77377, 77477, 77747, 77773, 77797, 77977, 79777, 79999, 88883, 94999, 97777
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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The sequence is probably infinite.
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EXAMPLE
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101117 has exactly four 1s.
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MAPLE
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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 10000 do p := ithprime(n) ; if isdgctm(p, 4) then printf("%d, ", p) ; fi; od: # R. J. Mathar, Jun 21 2009
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CROSSREFS
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Sequence in context: A114385 A144863 A058042 this_sequence A157711 A159863 A054037
Adjacent sequences: A161783 A161784 A161785 this_sequence A161787 A161788 A161789
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KEYWORD
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nonn,base
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AUTHOR
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Ki Punches (ki1212(AT)pocketmail.com), Jun 19 2009
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EXTENSIONS
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Edited and corrected by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 21 2009
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