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A355305
Carmichael numbers ending in 5.
5
1105, 2465, 10585, 62745, 278545, 449065, 825265, 1050985, 2531845, 3224065, 3664585, 5632705, 6054985, 9582145, 11119105, 12945745, 13187665, 13992265, 15403285, 21584305, 22665505, 28787185, 31692805, 36121345, 37354465, 39353665, 40280065, 41298985, 47006785, 60112885, 67371265, 74165065, 84417985
OFFSET
1,1
MATHEMATICA
Select[10*Range[0, 10^7] + 5, CompositeQ[#] && Divisible[# - 1, CarmichaelLambda[#]] &] (* Amiram Eldar, Jul 07 2022 *)
PROG
(PARI) Korselt(n) = my(f=factor(n)); for(i=1, #f[, 1], if(f[i, 2]>1||(n-1)%(f[i, 1]-1), return(0))); 1;
isok(n) = ((n%10)==5) && !isprime(n) && Korselt(n) && n>1; \\ Michel Marcus, Jul 07 2022; after A002997
(Python)
from itertools import islice
from sympy import factorint, nextprime
def A355305_gen(): # generator of terms
p, q = 3, 5
while True:
for n in range(p+2+(-p+3)%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)
A355305_list = list(islice(A355305_gen(), 10)) # Chai Wah Wu, Jul 24 2022
CROSSREFS
Intersection of A002997 and A017329.
Sequence in context: A214017 A083738 A265237 * A374269 A291602 A275881
KEYWORD
nonn,base
AUTHOR
Omar E. Pol, Jul 03 2022
STATUS
approved