A306086 Primes which remain prime after all odd digits are deleted.

2, 23, 29, 127, 211, 233, 239, 251, 257, 271, 277, 293, 521, 523, 727, 929, 1021, 1123, 1129, 1213, 1217, 1231, 1237, 1259, 1277, 1279, 1291, 1297, 1321, 1327, 1523, 1721, 1723, 2111, 2113, 2131, 2137, 2153, 2179, 2311, 2333, 2339, 2351, 2357, 2371, 2377, 2393, 2399, 2531, 2539, 2551, 2557, 2579, 2591, 2593

Offset

1,1

Comments

Consists of primes which have all odd digits except for a single digit 2 with any number of zeros before the 2 and none after it.

Links

Table of n, a(n) for n=1..55.

Example

251 is a member of this sequence because when all the odd digits are removed, the single digit left is 2.

Mathematica

Select[Prime@ Range@ 380, PrimeQ[ FromDigits[ Select[ IntegerDigits@#, EvenQ]]] &]

Prog

(PARI) isok(p) = isprime(p) && isprime(fromdigits(select(x->!(x % 2), digits(p)))); \\ Michel Marcus, Jun 21 2018

Crossrefs

Cf. A306084, A306085.

Sequence in context: A107148 A062653 A208272 * A045708 A090150 A106102

Adjacent sequences: A306083 A306084 A306085 * A306087 A306088 A306089

Keyword

nonn,base

Author

Zak Seidov and Robert G. Wilson v, Jun 20 2018

Status

approved