A364831 Contribution to the OEIS

 

A364831 Primes 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 (list; graph; refs; listen; history; edit; text; internal 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 Chai Wah Wu, Table of n, a(n) for n = 1..10000 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 Cf. A009996, A019546, A177061, A028867. Sequence in context: A214179 A178237 A118842 * A244595 A244597 A237439 Adjacent sequences: A364828 A364829 A364830 * A364832 A364833 A364834 KEYWORD nonn,base AUTHOR James C. McMahon, Aug 09 2023 STATUS approved