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A140366 a(n) = isprime(6n-1) + 2*isprime(6n-5), where isprime = A010051. 0
1, 3, 3, 3, 1, 2, 3, 3, 1, 1, 2, 3, 2, 3, 1, 0, 3, 3, 3, 0, 0, 3, 1, 2, 1, 2, 2, 3, 1, 1, 2, 1, 3, 2, 0, 2, 0, 3, 3, 1, 2, 1, 1, 1, 1, 2, 3, 2, 1, 0, 0, 3, 3, 0, 0, 2, 2, 1, 3, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The idea is to consider 2-bit words, where the least resp. most significant bit correspond to primality of the respective member in the couple (6n-1,6n-5). (It might have been more natural to inverse the correspondences, i.e. to associate the LSB to the smaller number of the pair.) - M. F. Hasler, Jun 16 2008

LINKS

Table of n, a(n) for n=1..60.

PROG

(PARI) a(n)=isprime(6*n-5)<<1+isprime(6*n-1) \\ M. F. Hasler, Jun 16 2008

CROSSREFS

Cf. A002476, A007528.

Sequence in context: A172364 A323596 A323375 * A167817 A153401 A181520

Adjacent sequences:  A140363 A140364 A140365 * A140367 A140368 A140369

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Jun 10 2008

EXTENSIONS

Edited by M. F. Hasler, Jun 16 2008

STATUS

approved

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Last modified October 7 06:27 EDT 2022. Contains 357270 sequences. (Running on oeis4.)