|
|
A229125
|
|
Numbers of the form p * m^2, where p is prime and m > 0: union of A228056 and A000040.
|
|
11
|
|
|
2, 3, 5, 7, 8, 11, 12, 13, 17, 18, 19, 20, 23, 27, 28, 29, 31, 32, 37, 41, 43, 44, 45, 47, 48, 50, 52, 53, 59, 61, 63, 67, 68, 71, 72, 73, 75, 76, 79, 80, 83, 89, 92, 97, 98, 99, 101, 103, 107, 108, 109, 112, 113, 116, 117, 124, 125, 127, 128, 131, 137, 139, 147, 148, 149
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
No term is the product of two other terms.
Squares of terms and pairwise products of distinct terms form a subsequence of A028260.
|
|
LINKS
|
|
|
FORMULA
|
The number of terms not exceeding x is (Pi^2/6) * x/log(x) + O(x/(log(x))^2) (Cohen, 1962). - Amiram Eldar, Jul 27 2020
|
|
MATHEMATICA
|
With[{nn=70}, Take[Union[Flatten[Table[p*m^2, {p, Prime[Range[nn]]}, {m, nn}]]], nn]] (* Harvey P. Dale, Dec 02 2014 *)
|
|
PROG
|
(PARI) test(n)=isprime(core(n))
for(n=1, 200, if(test(n), print1(n", ")))
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|