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A354923
a(n) = 1 if n is either a power of prime or 2*prime, otherwise 0.
2
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 0, 0, 1, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 1, 1, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 1, 0, 1, 1, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 1, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1
OFFSET
1
FORMULA
For n > 4, a(n) = A010055(n) + A353478(n).
MATHEMATICA
a[n_] := If[PrimePowerQ[n] || PrimeQ[n/2], 1, 0]; a[1] = 1; Array[a, 100] (* Amiram Eldar, Jun 13 2022 *)
PROG
(PARI) A354923(n) = ((1==n)|| isprimepower(n) || (!(n%2) && isprime(n/2)));
CROSSREFS
Characteristic function of A354925.
Cf. also A354924.
Sequence in context: A344884 A228710 A103447 * A354924 A353799 A123927
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jun 13 2022
STATUS
approved