A373477 a(n) = 1 if A001414(n) and A003415(n) are both multiples of 3, otherwise 0, where A001414 is the sum of prime factors with repetition, and A003415 is the arithmetic derivative.

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

Offset

1

Links

Antti Karttunen, Table of n, a(n) for n = 1..100000

Index entries for characteristic functions

Example

a(n) = [A373364(n) == 0 (mod 3)], where [ ] is the Iverson bracket.
a(n) >= A373474(n).

Prog

(PARI)
A001414(n) = ((n=factor(n))[, 1]~*n[, 2]); \\ From A001414.
A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
A373477(n) = (!(A001414(n)%3) && !(A003415(n)%3));

Crossrefs

Characteristic function of A373478.

Cf. A001414, A003415, A373364.

Cf. also A373474.

Sequence in context: A373975 A374110 A297199 * A185117 A014045 A015269

Adjacent sequences: A373474 A373475 A373476 * A373478 A373479 A373480

Keyword

nonn

Author

Antti Karttunen, Jun 07 2024

Status

approved