Thursday, May 9, 2024

A364831 Contribution to the OEIS

 

A364831Primes whose digits are prime and in nonincreasing order.1
2, 3, 5, 7, 53, 73, 733, 773, 5333, 7333, 7753, 55333, 75533, 75553, 77773, 733333, 755333, 775553, 7553333, 7555333, 7775533, 7777753, 55555333, 55555553, 77755553, 555553333, 755555533, 773333333, 777555553, 777773333, 777775333, 777775553, 777777773 (listgraphrefslistenhistoryedittextinternal format)
OFFSET
1,1
COMMENTS
Intersection of A028867 and A019546.
The subsequence for primes whose digits are prime and in strictly decreasing order has just six terms: 2 3 5 7 53 73 (see A177061).
LINKS
MATHEMATICA
Select[Prime[Range[3100000]], AllTrue[d = IntegerDigits[#], PrimeQ] && GreaterEqual @@ d &]
PROG
(Python)
from itertools import count, islice, chain, combinations_with_replacement
from sympy import isprime
def A364831_gen(): # generator of terms
yield 2
yield from chain.from_iterable((sorted(s for d in combinations_with_replacement('753', l) if isprime(s:=int(''.join(d)))) for l in count(1)))
A364831_list = list(islice(A364831_gen(), 30)) # Chai Wah Wu, Sep 10 2023
CROSSREFS
Sequence in context: A214179 A178237 A118842 * A244595 A244597 A237439
KEYWORD
nonn,base
AUTHOR
James C. McMahon, Aug 09 2023
STATUS
approved

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