A179025 - OEIS

%I #12 Feb 20 2022 18:51:12

%S 2,29,211,241,269,281,421,821,829,929,1021,1129,1201,1249,1289,1291,

%T 1429,1621,2011,2069,2081,2089,2099,2111,2141,2161,2411,2441,2609,

%U 2689,2699,2801,2819,2861,2909,2969,2999,4021,4129,4201,4211,4219,4241,4261

%N Primes with a single 2 as the only prime digit.

%C This is a proper subsequence of A179024. - _Jianing Song_, Jul 10 2018

%H Robert Israel, <a href="/A179025/b179025.txt">Table of n, a(n) for n = 1..10000</a>

%p Digs:= [0,1,2,4,6,8,9]:

%p f:= proc(n) local L,x;

%p   L:= convert(n,base,7);

%p   if numboccur(2,L) <> 1 then return NULL fi;

%p   x:= add(Digs[L[i]+1]*10^(i-1),i=1..nops(L));

%p   if isprime(x) then x fi

%p end proc:

%p map(f, [$1..2000]); # _Robert Israel_, Jul 10 2018

%t Select[Prime[Range[600]],DigitCount[#,10,2]==1&&NoneTrue[ DeleteCases[ IntegerDigits[#],2],PrimeQ]&] (* _Harvey P. Dale_, Feb 20 2022 *)

%Y Cf. A179024.

%K nonn,base

%O 1,1

%A _Lekraj Beedassy_, Jun 25 2010

%E Terms confirmed by _Ray Chandler_, Jul 13 2010

%E Definition clarified by _Harvey P. Dale_, Feb 20 2022