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

Author

Ki Punches, Jun 19 2009

Keywords

• nonn
• base

Comments

The sequence is probably infinite.

Examples

			101117 has exactly four 1s.
		

Links

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

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 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 *)

Extensions

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