A046892 Number of permutations of digits of A046891(n) that are primes.

0, 1, 2, 3, 4, 5, 8, 9, 10, 11, 13, 16, 18, 22, 31, 34, 37, 39, 40, 49, 52, 64, 80, 87, 93, 115, 121, 144, 149, 160, 172, 225, 233, 298, 299, 308, 384, 399, 408, 423, 475, 484, 569, 571, 738, 806, 835, 863, 934, 1247, 1413, 1525, 1739, 1775, 2282, 2303, 2325

Offset: 1

Author

David W. Wilson

Keywords

• nonn
• base

Links

• Michael S. Branicky, Table of n, a(n) for n = 1..91

Crossrefs

Cf. A039999, A046891.

Programs

Mathematica

a = {}; b = -1; Do[c = Count[ PrimeQ[ FromDigits /@ Permutations[IntegerDigits[n]]], True]; If[c > b, b = c; a = Append[a, c]], {n, 1, 10^8}]; a

Python

from sympy import prime
from gmpy2 import is_prime
from sympy.utilities.iterables import multiset_permutations as mp
from itertools import count, islice, combinations_with_replacement as mc
def f(n): return sum(1 for p in mp(str(n)) if is_prime(t:=int("".join(p))))
def bgen(d):
    for f in "123456789":
        yield from map(int, (f+"".join(m) for m in mc("0123456789", d-1)))
def agen():
    record = -1
    for d in count(1):
        for k in bgen(d):
            v = f(k)
            if v > record:
                record = v
                yield v
print(list(islice(agen(), 30))) # Michael S. Branicky, Feb 17 2024