A046891 Values of n where number of permutations of digits a(n) that are prime increases.

1, 2, 13, 103, 107, 1007, 1013, 1049, 1079, 1237, 10013, 10039, 10079, 10139, 10237, 10279, 10379, 13789, 100127, 100139, 100235, 100237, 100279, 101237, 101239, 102347, 102367, 102379, 103579, 103789, 1001234, 1001237, 1001239, 1002347, 1002359, 1002367, 1002379

Offset

1,2

Links

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

Mathematica

ap[n_] := Count[FromDigits /@ Permutations[IntegerDigits[n]], _?PrimeQ]; t = {1}; x = 0; Do[If[ap[i] > x, AppendTo[t, i]; x = ap[i]], {i, 105000}]; t (* Jayanta Basu, Jun 29 2013 *)

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 k
print(list(islice(agen(), 30))) # Michael S. Branicky, Feb 17 2024

Crossrefs

Cf. A039999, A046892.

Sequence in context: A371578 A266906 A107000 * A046893 A354159 A126036

Adjacent sequences: A046888 A046889 A046890 * A046892 A046893 A046894

Keyword

nonn,base

Author

David W. Wilson

Extensions

a(35) and beyond from Michael S. Branicky, Feb 17 2024

Status

approved