A285227 Primes with integer arithmetic mean of digits = 7 in base 10.

7, 59, 1999, 3889, 4789, 4969, 4987, 5689, 5779, 5869, 6679, 6949, 6967, 7489, 7669, 7687, 7759, 7867, 7993, 8389, 8677, 8839, 8893, 8929, 9199, 9397, 9649, 9739, 9829, 9883, 9973, 18899, 19889, 19979, 19997, 28979, 29789, 29879, 35999, 36899, 37799, 37889

Offset

1,1

Links

Jaroslav Krizek, Table of n, a(n) for n = 1..1000

Mathematica

Select[Prime@ Range@ PrimePi@ 40000, Mean@ IntegerDigits@ # == 7 &] (* Michael De Vlieger, Apr 22 2017 *)

Prog

(Magma) [n: n in [1..100000] | IsPrime(n) and &+Intseq(n) mod #Intseq(n) eq 0 and &+Intseq(n) / #Intseq(n) eq 7]
(Python)
from itertools import count, islice
from collections import Counter
from sympy.utilities.iterables import partitions, multiset_permutations
from sympy import isprime
def A285227_gen(): # generator of terms
    yield 7
    for l in count(2):
        for i in range(1, 10):
            yield from sorted(q for q in (int(str(i)+''.join(map(str, j))) for s, p in partitions(7*l-i, m=l-1, k=9, size=True) for j in multiset_permutations([0]*(l-1-s)+list(Counter(p).elements()))) if isprime(q))
A285227_list = list(islice(A285227_gen(), 30)) # Chai Wah Wu, Nov 29 2023

Crossrefs

Primes from A061424. Subsequence of A069709.

Sequences of primes such that a(n) = k for k = 1, 2, 4, 5, 7 and 8: A069710 (k = 1), A285096 (k = 2), A285225 (k = 4), A285226 (k = 5), this sequence (k = 7), A285228 (k = 8).

Sequence in context: A331709 A203174 A183260 * A358132 A063969 A366613

Adjacent sequences: A285224 A285225 A285226 * A285228 A285229 A285230

Keyword

nonn,base

Author

Jaroslav Krizek, Apr 19 2017

Status

approved