cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A161848 Primes with at least one digit appearing exactly three times in the decimal expansion.

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%I A161848 #7 Feb 21 2019 23:15:40
%S A161848 1117,1151,1171,1181,1511,1777,1811,1999,2111,2221,2333,2777,2999,
%T A161848 3313,3323,3331,3343,3373,3433,3533,3733,3833,4111,4441,4447,4999,
%U A161848 5333,5557,6661,7177,7333,7477,7577,7717,7727,7757,7877,8111,8887,8999,9199,9929
%N A161848 Primes with at least one digit appearing exactly three times in the decimal expansion.
%C A161848 Sequence is probably infinite.
%e A161848 2333, 3313, 3833 all repeat some digit 3 three times.
%p A161848 isdgctm := proc(n,d) local dgs,a,i ; dgs := convert(n,base,10) ; a := [seq(0,j=0..9)] ;
%p A161848 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:
%p A161848 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
%Y A161848 Cf. A161786, A161796.
%K A161848 nonn,base
%O A161848 1,1
%A A161848 _Ki Punches_, Jun 20 2009
%E A161848 Edited and corrected by _R. J. Mathar_, Jun 21 2009