A379955 a(n) = 1 if n = floor(prime(i)/2) * prime(i)^e, for some e, i > 0, otherwise 0, where prime(i) = A000040(i).

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

Offset

1

Links

Antti Karttunen, Table of n, a(n) for n = 1..100949

Index entries for characteristic functions.

Prog

(PARI) A379955(n) = { my(f=factor(n)); sum(i=1, #f~, ((n/(f[i, 1]^f[i, 2])) == (f[i, 1]\2))); };

Crossrefs

Characteristic function of A379956.

Cf. A000040, A130290, A217983.

Sequence in context: A200263 A373153 A051067 * A288858 A356313 A309218

Adjacent sequences: A379952 A379953 A379954 * A379956 A379957 A379958

Keyword

nonn,new

Author

Antti Karttunen, Jan 16 2025

Status

approved