A340369 a(n) = 1 if n has at most 3 prime factors when counted with multiplicity, 0 otherwise.

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1

Offset

1

Links

Antti Karttunen, Table of n, a(n) for n = 1..65537

Index entries for characteristic functions

Index entries for sequences computed from exponents in factorization of n

Formula

a(n) = [A001222(n) <= 3], where [ ] is the Iverson bracket.

Prog

(PARI) A340369(n) = (bigomega(n)<=3);

Crossrefs

Characteristic function of A037144.

Cf. A001222.

Cf. also A101040.

Sequence in context: A340372 A167850 A167851 * A307445 A363552 A307430

Adjacent sequences: A340366 A340367 A340368 * A340370 A340371 A340372

Keyword

nonn

Author

Antti Karttunen, Jan 06 2021

Status

approved