A085557 Numbers that have more prime digits than nonprime digits.

2, 3, 5, 7, 22, 23, 25, 27, 32, 33, 35, 37, 52, 53, 55, 57, 72, 73, 75, 77, 122, 123, 125, 127, 132, 133, 135, 137, 152, 153, 155, 157, 172, 173, 175, 177, 202, 203, 205, 207, 212, 213, 215, 217, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230, 231, 232

Offset

1,1

Comments

Begins to differ from A046034 at the 21st term (which is the first 3-digit term).

Links

David A. Corneth, Table of n, a(n) for n = 1..10000

Example

133 is in the sequence as the prime digits are 3 and 3 (those are two digits; counted with multiplicity) and one nonprime digit 1 and so there are more prime digits than nonprime digits. - David A. Corneth, Sep 06 2020

Prog

(PARI) is(n) = my(d = digits(n), c = 0); for(i = 1, #d, if(isprime(d[i]), c++)); c<<1 > #d \\ David A. Corneth, Sep 06 2020
(Python)
from itertools import count, islice
def A085557_gen(startvalue=1): # generator of terms
    return filter(lambda n:len(s:=str(n))<(sum(1 for d in s if d in {'2', '3', '5', '7'})<<1), count(max(startvalue, 1)))
A085557_list = list(islice(A085557_gen(), 20)) # Chai Wah Wu, Feb 08 2023

Crossrefs

Cf. A193238, A046034, A046035, A118950, A019546, A203263, A035232, A039996, A085823, A052382, A084544, A084984, A017042, A001743, A001744, A014261, A014263, A202267, A202268, A211681.

Sequence in context: A024768 A024769 A340112 * A125665 A046034 A062087

Adjacent sequences: A085554 A085555 A085556 * A085558 A085559 A085560

Keyword

nonn,easy,base

Author

Jason Earls, Jul 04 2003

Status

approved