|
|
A226016
|
|
Primes with alternate digits even and odd, and most significant digit even.
|
|
1
|
|
|
2, 23, 29, 41, 43, 47, 61, 67, 83, 89, 2129, 2141, 2143, 2161, 2309, 2341, 2347, 2381, 2383, 2389, 2503, 2521, 2543, 2549, 2707, 2729, 2741, 2749, 2767, 2789, 2903, 2909, 2927, 2963, 2969, 4127, 4129, 4327, 4349, 4363, 4507, 4523, 4547, 4549, 4561, 4567, 4583
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
The only difference compared to A068887 is that the 3 is missing here. - R. J. Mathar, May 26 2013
|
|
LINKS
|
|
|
EXAMPLE
|
2143 is a member since its digits are alternatively even and odd.
|
|
MATHEMATICA
|
a[n_, k_]:=Union[Boole/@EvenQ[Take[IntegerDigits[n], {k, -1, 2}]]]; Join[{2}, Select[Prime[Range[5, 620]], {a[#, 1], a[#, 2]}=={{1}, {0}} &]]
Select[Prime[Range[1000]], Boole[EvenQ[IntegerDigits[#]]]==PadRight[{}, IntegerLength[#], {1, 0}]&] (* Harvey P. Dale, Oct 28 2023 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,base
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|