A046890 a(n) is the least integer that has exactly n anagrams that are primes.

1, 2, 13, 113, 149, 1013, 1039, 1247, 1123, 1349, 1579, 1237, 10127, 10238, 10139, 10235, 10234, 10457, 11579, 10789, 10237, 11239, 12457, 10279, 12349, 12347, 13678, 12359, 14579, 13489, 10379, 12367, 12389, 23579, 13579, 100349, 12379

Offset

0,2

Comments

An anagram is a permutation of digits not beginning with 0.

Links

Michael S. Branicky, Table of n, a(n) for n = 0..8004 (search of numbers with <= 12 digits; terms 0..511 from Chai Wah Wu)

Mathematica

ap[n_] := Count[FromDigits /@ Select[Permutations[IntegerDigits[n]], First[#] != 0 &], _?PrimeQ]; t = {1}; Do[i = 1; While[ap[i] != n, i++]; AppendTo[t, i], {n, 30}]; t (* Jayanta Basu, Jun 29 2013 *)

Prog

(Python)
from sympy import isprime
from sympy.utilities.iterables import multiset_permutations as mp
from itertools import count, islice, combinations_with_replacement as mc
def nd(d): yield from ("".join((f, )+m) for f in "123456789" for m in mc("0123456789", d-1))
def c(s): return sum(1 for p in mp(s) if p[0]!="0" and isprime(int("".join(p))))
def agen(): # generator of sequence terms
    n, adict = 0, dict()
    for digs in count(1):
        for s in nd(digs):
            v = c(s)
            if v not in adict: adict[v] = int(s)
            while n in adict: yield adict[n]; n += 1
print(list(islice(agen(), 40))) # Michael S. Branicky, Feb 08 2023

Crossrefs

Cf. A046810.

Sequence in context: A277463 A277469 A046888 * A166921 A046811 A046813

Adjacent sequences: A046887 A046888 A046889 * A046891 A046892 A046893

Keyword

nonn,base

Author

David W. Wilson

Status

approved