A369655 a(n) = 1 if n' is odd and also n'' is odd, otherwise 0, where n' stands for the arithmetic derivative, A003415.

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

Offset

0

Links

Antti Karttunen, Table of n, a(n) for n = 0..100000

Index entries for characteristic functions

Formula

a(n) = A165560(n) * A165560(A003415(n)).

Prog

(PARI)
A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
A369655(n) = { my(u=A003415(n)); ((u%2) && (A003415(u)%2)); };

Crossrefs

Characteristic function of A369656.

Cf. A000035, A003415, A068346, A165560.

Sequence in context: A169671 A070108 A341995 * A369965 A011675 A096094

Adjacent sequences: A369652 A369653 A369654 * A369656 A369657 A369658

Keyword

nonn

Author

Antti Karttunen, Feb 05 2024

Status

approved