A378540 a(n) = 1 if n is a practical number (A005153) that is neither a square or twice a square, otherwise a(n) = 0.

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

Offset

1

Links

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

Index entries for characteristic functions

Formula

a(n) = (1-A053866(n)) * A322860(n).

a(n) <= A179527(n).

Prog

(PARI) A378540(n) = (!(sigma(n)%2) && is_A005153(n));

Crossrefs

Characteristic function of A378541.

Differs from A179527 on n given by A353061.

Cf. A000203, A005153, A053866, A322860.

Sequence in context: A378449 A286925 A378598 * A179527 A353528 A358755

Adjacent sequences: A378537 A378538 A378539 * A378541 A378542 A378543

Keyword

nonn

Author

Antti Karttunen, Dec 02 2024

Status

approved