A352970 Carmichael numbers ending in 9.

1729, 294409, 1033669, 1082809, 1773289, 5444489, 7995169, 8719309, 17098369, 19384289, 23382529, 26921089, 37964809, 43620409, 45890209, 50201089, 69331969, 84311569, 105309289, 114910489, 146843929, 168659569, 172947529, 180115489, 188516329, 194120389, 214852609, 228842209, 230996949, 246446929, 271481329

Offset

1,1

Comments

The first term is the Hardy-Ramanujan number.

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..109 from Chai Wah Wu)

Index entries for sequences related to Carmichael numbers.

Mathematica

Select[10*Range[0, 3*10^7] + 9, CompositeQ[#] && Divisible[# - 1, CarmichaelLambda[#]] &] (* Amiram Eldar, May 28 2022 *)

Prog

(Python)
from itertools import islice
from sympy import factorint, nextprime
def A352970_gen(): # generator of terms
    p, q = 3, 5
    while True:
        for n in range(p+11-((p+2) % 10), q, 10):
            f = factorint(n)
            if max(f.values()) == 1 and not any((n-1) % (p-1) for p in f):
                yield n
        p, q = q, nextprime(q)
A352970_list = list(islice(A352970_gen(), 5)) # Chai Wah Wu, May 11 2022

Crossrefs

Intersection of A002997 and A017377.

Subsequence of A053181.

Cf. A001235, A354609, A355305, A355307, A355309.

Sequence in context: A318646 A182087 A327787 * A033502 A277366 A050794

Adjacent sequences: A352967 A352968 A352969 * A352971 A352972 A352973

Keyword

nonn,base

Author

Omar E. Pol, Apr 12 2022

Status

approved