A161786 Primes with at least one digit appearing exactly four times in the decimal expansion.

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

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