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A161786 Primes with at least one digit appearing exactly four times in the decimal expansion. 5
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; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The sequence is probably infinite.

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..2000

EXAMPLE

101117 has exactly four 1s.

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 10000 do p := ithprime(n) ; if isdgctm(p, 4) then printf("%d, ", p) ; fi; od: # R. J. Mathar, Jun 21 2009

MATHEMATICA

Select[Prime[Range[186, 10000]], MemberQ[DigitCount[#], 4]&] (* Harvey P. Dale, Apr 12 2015 *)

CROSSREFS

Sequence in context: A058042 A191244 A269066 * A157711 A159863 A234180

Adjacent sequences:  A161783 A161784 A161785 * A161787 A161788 A161789

KEYWORD

nonn,base

AUTHOR

Ki Punches, Jun 19 2009

EXTENSIONS

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

STATUS

approved

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Last modified May 14 19:53 EDT 2021. Contains 343903 sequences. (Running on oeis4.)