login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A126043
Exponents p of the Mersenne primes 2^p - 1 (see A000043) read mod 3.
18
2, 0, 2, 1, 1, 2, 1, 1, 1, 2, 2, 1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 2, 2, 2, 2, 1, 1, 2, 1, 1, 1, 2, 2, 1, 2, 2, 2, 2, 1, 1, 1, 2, 1, 2, 2, 1, 2, 2
OFFSET
1,1
FORMULA
a(n) = A010872(A000043(n)). - Michel Marcus, Aug 12 2014
MATHEMATICA
Array[Mod[MersennePrimeExponent@ #, 3] &, 45] (* Michael De Vlieger, Apr 07 2018 *)
PROG
(PARI) forprime(p=1, 1e3, if(isprime(2^p-1), print1(p%3, ", "))) \\ Felix Fröhlich, Aug 12 2014
CROSSREFS
Cf. A000043, A010872 (n mod 3), A126044-A126059.
Sequence in context: A104450 A281460 A035226 * A360170 A306659 A191225
KEYWORD
nonn,more
AUTHOR
Artur Jasinski, Dec 17 2006
EXTENSIONS
a(45)-a(47) from Ivan Panchenko, Apr 08 2018
a(48) from Amiram Eldar, Oct 14 2024
STATUS
approved