A355444 a(n) = 1 if n is of the form p^2 * q where p and q are primes with p < q < p^2, otherwise 0.

0, 0, 0, 0, 0, 0, 0, 0, 0, 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, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 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, 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, 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..100000

Index entries for characteristic functions

Formula

a(n) = A353472(n) * A355454(n).

a(n) = A353474(n) - A355443(n).

Mathematica

a[n_] := If[(f = FactorInteger[n])[[;; , 2]] == {2, 1} && f[[1, 1]]^2 > f[[2, 1]], 1, 0]; Array[a, 100] (* Amiram Eldar, Jul 07 2022 *)

Prog

(PARI) A355444(n) = ((numdiv(n) == (3+bigomega(n))) && issquare(divisors(n)[4]));

Crossrefs

Characteristic function of A355446.

Cf. A353472, A353474, A355443, A355454.

Sequence in context: A277163 A011726 A297041 * A070109 A355454 A107846

Adjacent sequences: A355441 A355442 A355443 * A355445 A355446 A355447

Keyword

nonn

Author

Antti Karttunen, Jul 02 2022

Status

approved