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A028867
Primes with digits in nonincreasing order.
11
2, 3, 5, 7, 11, 31, 41, 43, 53, 61, 71, 73, 83, 97, 211, 311, 331, 421, 431, 433, 443, 521, 541, 631, 641, 643, 653, 661, 733, 743, 751, 761, 773, 811, 821, 853, 863, 877, 881, 883, 887, 911, 941, 953, 971, 977, 983, 991, 997, 2111, 2221, 3221
OFFSET
1,1
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..10000 (terms n = 1..1000 from T. D. Noe)
MATHEMATICA
t={}; Do[p=Prime[n]; If[Select[Differences[IntegerDigits[p]], #>0&]=={}, AppendTo[t, p]], {n, 460}]; t (* Jayanta Basu, May 04 2013 *)
Select[Prime[Range[600]], Max[Differences[IntegerDigits[#]]]<1&] (* Harvey P. Dale, Oct 30 2013 *)
PROG
(PARI) is(n)=my(d=digits(n)); for(i=2, #d, if(d[i]>d[i-1], return(0))); isprime(n) \\ Charles R Greathouse IV, Aug 18 2017
(Python)
from itertools import count, islice, combinations_with_replacement
from sympy import isprime
def A028867_gen(): # generator of terms
yield from (2, 3, 5, 7)
a, b = {'1':1, '2':1, '3':2, '4':2, '5':2, '6':2, '7':3, '8':3, '9':4}, (1, 3, 7, 9)
for l in count(1):
mlist = []
for d in combinations_with_replacement('987654321', l):
k = 10*int(''.join(d))
for e in b[:a[d[-1]]]:
if isprime(m:=k+e):
mlist.append(m)
yield from sorted(mlist)
A028867_list = list(islice(A028867_gen(), 30)) # Chai Wah Wu, Dec 25 2023
CROSSREFS
KEYWORD
nonn,base
EXTENSIONS
Definition corrected by Omar E. Pol, Mar 22 2012
STATUS
approved