OFFSET
1,1
COMMENTS
The largest term is the prime 99999999988888888777777766666655555444223343.
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..10000
EXAMPLE
In the prime 3313 the digit "1" appears exactly one time and the digit "3" appears exactly three times.
MATHEMATICA
ddp[x_]:=Select[FromDigits/@Permutations[Flatten[PadRight[{}, #, #]&/@x]], PrimeQ]; Take[Flatten[ddp/@Subsets[Range[5]]]//Sort, 40] (* Harvey P. Dale, May 13 2020 *)
PROG
(Python)
from sympy import isprime
from itertools import chain, combinations as C, count, islice
from sympy.utilities.iterables import multiset_permutations as mp
def powerset(s):
return chain.from_iterable(C(s, r) for r in range(len(s)+1))
def agen():
sumlst = [[] for i in range(46)]
for s in powerset(range(1, 10)): sumlst[sum(s)].append(s)
for numdigits in count(1):
found = set()
for t in sumlst[numdigits]:
diglst = "".join(str(i)*i for i in t)
for m in mp(diglst, numdigits):
t = int("".join(m))
if isprime(t): found.add(t)
yield from sorted(found)
print(list(islice(agen(), 30))) # Michael S. Branicky, Aug 10 2022
CROSSREFS
KEYWORD
base,easy,fini,nonn
AUTHOR
Carlos Rivera, Nov 22 2002
STATUS
approved