A340372 a(n) = 1 if n has no more than one odd prime factor to an odd power in its prime factorization, 0 otherwise.

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

Offset

1

Links

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

Index entries for characteristic functions

Formula

a(n) = [A162642(A000265(n)) <= 1], where [ ] is the Iverson bracket.

For all n, a(n) >= A340363(n) >= A340373(n).

Prog

(PARI) A340372(n) = (2>(#select(t->(t%2), factor(n>>valuation(n, 2))[, 2]))); \\ After code in A285801.

Crossrefs

Characteristic function of A285801.

Cf. A000265, A162642.

Cf. also A340363, A340373.

Sequence in context: A296079 A354806 A340363 * A167850 A167851 A340369

Adjacent sequences: A340369 A340370 A340371 * A340373 A340374 A340375

Keyword

nonn

Author

Antti Karttunen, Jan 06 2021

Status

approved