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A364251
a(n) = 1 if n is of the form q*(2^k), where q is one of the Mersenne primes (A000668) and k >= 0, otherwise a(n) = 0.
4
0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0
OFFSET
1
FORMULA
a(n) = [A331410(n) == 1], where [ ] is the Iverson bracket.
a(n) = [A364260(n) == 1].
a(n) <= A336923(n) <= A364252(n).
PROG
(PARI)
isA000668(n) = (isprime(n)&&!bitand(n, 1+n));
A364251(n) = isA000668(n>>valuation(n, 2));
CROSSREFS
Characteristic function of A335431.
Cf. also A336923, A364252.
Sequence in context: A028999 A091244 A189632 * A365421 A131378 A354029
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jul 16 2023
STATUS
approved