A370122 a(n) = 1 if the second arithmetic derivative of n is a multiple of 3, otherwise 0.

1, 1, 1, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 1, 0, 1, 0, 0, 0, 1, 1, 1, 1, 1, 0, 1, 1, 0, 1, 0, 0, 1, 1, 1, 0, 0, 0, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 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) = A079978(A068346(n)) = A359430(A003415(n)).

a(n) = A370118(n) + A369658(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]));
A068346(n) = A003415(A003415(n));
A370122(n) = (0==(A068346(n)%3));

Crossrefs

Characteristic function of A370123.

Cf. A003415, A068346, A079978, A359430, A369658, A370118.

Sequence in context: A181650 A115952 A115524 * A117198 A271047 A054525

Adjacent sequences: A370119 A370120 A370121 * A370123 A370124 A370125

Keyword

nonn

Author

Antti Karttunen, Feb 10 2024

Status

approved