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A253595 Least Carmichael number that is divisible by the n-th cyclic number A003277(n). 2
561, 1105, 1729, 561, 1105, 62745, 561, 1729, 6601, 2465, 2821, 561, 825265, 29341, 6601, 334153, 62745, 561, 2433601, 74165065, 29341, 1105, 8911, 116150434401, 10024561, 10585, 41041, 2508013, 55462177, 1105, 11921001 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,1

COMMENTS

Has any odd cyclic number at least one Carmichael multiple?

LINKS

Tim Johannes Ohrtmann and Max Alekseyev, Table of n, a(n) for n = 3..853

Open Problem Garden, Michon's conjecture

GĂ©rard P. Michon, Carmichael Multiples of Odd Cyclic Numbers

EXAMPLE

a(8) = 62745 because this is the least Carmichael number which is divisible by 15 (the 8th cyclic number).

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

isA002997(n)=n%2 && !isprime(n) && Korselt(n) && n>1

a(n) = {on = odd cyclic number(n); cn = 1; until (isA002997(cn) && (cn % on == 0), cn++); cn; }

CROSSREFS

Cf. A002997, A003277, A135721.

Sequence in context: A141705 A135721 A290486 * A047713 A006971 A270698

Adjacent sequences:  A253592 A253593 A253594 * A253596 A253597 A253598

KEYWORD

nonn

AUTHOR

Tim Johannes Ohrtmann, Jan 05 2015

EXTENSIONS

a(292)-a(853) from Max Alekseyev, Apr 26 2015

STATUS

approved

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Last modified July 22 00:25 EDT 2018. Contains 312888 sequences. (Running on oeis4.)