A354925 - OEIS

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

(list; graph; refs; listen; history; text; internal format)

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