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A353798
a(n) = 1 if n is either 4th power of a prime (A030514), or product of a prime and the square of a different prime (A054753), otherwise 0.
1
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 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, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 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, 0, 0, 1, 0
OFFSET
1
FORMULA
a(n) = [floor(A101296(n)/2) == 3], where [ ] is the Iverson bracket, giving in this case 1 only if the prime signature class of n (A101296) is either 6 or 7.
a(n) >= A353472(n).
MATHEMATICA
a[n_] := If[MemberQ[{{4}, {1, 2}, {2, 1}}, FactorInteger[n][[;; , 2]]], 1, 0]; Array[a, 100] (* Amiram Eldar, May 13 2022 *)
PROG
(PARI) A353798(n) = { my(f=factor(n)[, 2]~); (f==[4] || f==[2, 1] || f==[1, 2]); }; \\ From function "is" in A080258
CROSSREFS
Characteristic function of A080258.
Sequence in context: A355447 A045701 A277156 * A193095 A011725 A346619
KEYWORD
nonn
AUTHOR
Antti Karttunen, May 13 2022
STATUS
approved

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