A028867 Primes with digits in nonincreasing order.

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

Cf. A052014, A028864, A052015.

Sequence in context: A155081 A157158 A155833 * A104154 A123214 A119834

Adjacent sequences: A028864 A028865 A028866 * A028868 A028869 A028870

Keyword

nonn,base

Author

Patrick De Geest

Extensions

Definition corrected by Omar E. Pol, Mar 22 2012

Status

approved