A354925 Union of powers of primes and even semiprimes.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 16, 17, 19, 22, 23, 25, 26, 27, 29, 31, 32, 34, 37, 38, 41, 43, 46, 47, 49, 53, 58, 59, 61, 62, 64, 67, 71, 73, 74, 79, 81, 82, 83, 86, 89, 94, 97, 101, 103, 106, 107, 109, 113, 118, 121, 122, 125, 127, 128, 131, 134, 137, 139, 142, 146, 149, 151, 157, 158, 163, 166, 167, 169

Offset

1,2

Links

Table of n, a(n) for n=1..76.

Mathematica

Join[{1}, Select[Range[170], PrimePowerQ[#] || PrimeQ[#/2] &]] (* Amiram Eldar, Jun 13 2022 *)

Prog

(PARI)
A354923(n) = ((1==n)|| isprimepower(n) || (!(n%2) && isprime(n/2)));
isA354925(n) = A354923(n);

Crossrefs

Union of A000961 and A100484.

Apart from {1}, complement of A265128.

Cf. A354923 (characteristic function).

Sequence in context: A195044 A033112 A049813 * A362184 A368904 A229991

Adjacent sequences: A354922 A354923 A354924 * A354926 A354927 A354928

Keyword

nonn

Author

Antti Karttunen, Jun 13 2022

Status

approved