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A355443
a(n) = 1 if n is of the form p^2 * q where p and q are primes with p^2 < q, otherwise 0.
4
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, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 0
OFFSET
1
FORMULA
a(n) = A353472(n) * A355453(n).
a(n) = A353474(n) - A355444(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) A355443(n) = ((numdiv(n) == (3+bigomega(n))) && issquare(divisors(n)[3]));
CROSSREFS
Characteristic function of A355445.
Sequence in context: A324731 A011734 A276653 * A011733 A297045 A304570
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jul 02 2022
STATUS
approved