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

1,3

Links

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

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

Prog

(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

Crossrefs

Cf. A039999, A046891.

Sequence in context: A047369 A004827 A155941 * A068406 A276878 A047247

Adjacent sequences: A046889 A046890 A046891 * A046893 A046894 A046895

Keyword

nonn,base

Author

David W. Wilson

Status

approved