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A359475
a(n) = 1 if n is a cubefree nonsquare whose factorization into a product of primes contains exactly one square, otherwise 0.
3
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 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, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0
OFFSET
1
FORMULA
a(n) = A049240(n) * A359474(n) = A359474(n) - A302048(n).
a(n) <= A359471(n).
Sum_{k=1..n} a(k) ~ c * n, where c = A271971. - Amiram Eldar, Jan 05 2023
MATHEMATICA
a[n_] := If[PrimeNu[n] > 1 && PrimeOmega[n] - PrimeNu[n] == 1, 1, 0]; Array[a, 100] (* Amiram Eldar, Jan 05 2023 *)
PROG
(PARI) A359475(n) = (omega(n) > 1) && (bigomega(n) - omega(n) == 1); \\ From "isok" function given in A072357 by Michel Marcus, Jul 16 2015
CROSSREFS
Characteristic function of A072357.
Sequence in context: A323547 A294930 A353472 * A294937 A363131 A355447
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jan 04 2023
STATUS
approved