A355305 - OEIS

A355305

Carmichael numbers ending in 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

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OFFSET

1,1

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

Index entries for sequences related to Carmichael numbers

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.

Cf. A352970, A354609, A355307, A355309.

Sequence in context: A214017 A083738 A265237 * A374269 A291602 A275881

Adjacent sequences: A355302 A355303 A355304 * A355306 A355307 A355308

KEYWORD

nonn,base

AUTHOR

Omar E. Pol, Jul 03 2022

STATUS

approved