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A232764
Numbers n such that the concatenation A000461(d_1)//A000461(d_2)//...//A000461(d_k) is prime, where d_i is the i-th digit of n and n is k digits long.
0
11, 31, 53, 101, 110, 131, 149, 159, 169, 189, 223, 231, 243, 249, 283, 297, 301, 310, 311, 313, 327, 331, 361, 381, 397, 429, 437, 453, 463, 503, 513, 530, 533, 561, 627, 641, 651, 657, 691, 779, 813, 861, 937, 941, 951, 961, 973, 1001, 1010, 1031, 1049, 1059, 1069
OFFSET
1,1
COMMENTS
If one of the digits is 0, it is read "zero zeros" and the term is thus omitted from the concatenation.
There are infinitely many numbers in this sequence. Any number can have an infinite number of 0's in its decimal expansion.
EXAMPLE
For n = 53, this becomes 5 fives and then 3 threes = 55555333. Since 55555333 is prime, 53 is a member of this sequence.
PROG
(Python)
import sympy
from sympy import isprime
def a():
..for n in range(1, 10**4):
....num = ''
....lst = list(str(n))
....for i in lst:
......num += i*int(i)
....if isprime(int(num)):
......print(n)
a()
CROSSREFS
Cf. A000461.
Sequence in context: A377460 A031287 A230329 * A057630 A057628 A144364
KEYWORD
nonn,base
AUTHOR
Derek Orr, Jun 01 2014
STATUS
approved