|
|
A179025
|
|
Primes with a single 2 as the only prime digit.
|
|
2
|
|
|
2, 29, 211, 241, 269, 281, 421, 821, 829, 929, 1021, 1129, 1201, 1249, 1289, 1291, 1429, 1621, 2011, 2069, 2081, 2089, 2099, 2111, 2141, 2161, 2411, 2441, 2609, 2689, 2699, 2801, 2819, 2861, 2909, 2969, 2999, 4021, 4129, 4201, 4211, 4219, 4241, 4261
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
|
|
LINKS
|
|
|
MAPLE
|
Digs:= [0, 1, 2, 4, 6, 8, 9]:
f:= proc(n) local L, x;
L:= convert(n, base, 7);
if numboccur(2, L) <> 1 then return NULL fi;
x:= add(Digs[L[i]+1]*10^(i-1), i=1..nops(L));
if isprime(x) then x fi
end proc:
|
|
MATHEMATICA
|
Select[Prime[Range[600]], DigitCount[#, 10, 2]==1&&NoneTrue[ DeleteCases[ IntegerDigits[#], 2], PrimeQ]&] (* Harvey P. Dale, Feb 20 2022 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,base
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|