A354923 - OEIS

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A354923

a(n) = 1 if n is either a power of prime or 2*prime, otherwise 0.

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

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OFFSET

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..100000

Index entries for characteristic functions

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