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A309741 Numbers k such that 6*10^(2*k) + 6*10^k + 1 are prime. 1
0, 1, 2, 4, 22, 133, 567 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
LINKS
EXAMPLE
13 is prime. ==> a(1) = 0.
661 is prime. ==> a(2) = 1.
60601 is prime. ==> a(3) = 2.
6006001 = 2027 * 2963.
600060001 is prime. ==> a(4) = 4.
PROG
(PARI) for(k=0, 1e3, if(ispseudoprime(6*100^k+6*10^k+1), print1(k", ")))
CROSSREFS
Cf. A309739.
Sequence in context: A235938 A279705 A321248 * A110130 A259116 A283322
KEYWORD
nonn,more,base
AUTHOR
Seiichi Manyama, Aug 15 2019
STATUS
approved

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Last modified March 29 06:44 EDT 2024. Contains 371265 sequences. (Running on oeis4.)