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A177492 Products of squares of 2 or more distinct primes. 5
36, 100, 196, 225, 441, 484, 676, 900, 1089, 1156, 1225, 1444, 1521, 1764, 2116, 2601, 3025, 3249, 3364, 3844, 4225, 4356, 4761, 4900, 5476, 5929, 6084, 6724, 7225, 7396, 7569, 8281, 8649, 8836, 9025, 10404, 11025, 11236, 12100, 12321, 12996, 13225 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
a(n) = (A120944(n))^2. - R. J. Mathar, Dec 06 2010
EXAMPLE
36=2^2*3^2, 100=2^2*5*2, 196=2^2*7^2,..900=2^2*3^2*5^2,..
MATHEMATICA
f1[n_]:=Length[Last/@FactorInteger[n]]; f2[n_]:=Union[Last/@FactorInteger[n]]; lst={}; Do[If[f1[n]>1&&f2[n]=={2}, AppendTo[lst, n]], {n, 0, 8!}]; lst
Reap[Do[{p, e} = Transpose[FactorInteger[n]]; If[Length[p]>1 && Union[e]=={2}, Sow[n]], {n, 13225}]][[2, 1]]
(* Second program *)
Select[Range[120], And[CompositeQ[#], SquareFreeQ[#]] &]^2 (* Michael De Vlieger, Aug 17 2023 *)
CROSSREFS
Sequence in context: A303661 A175391 A030627 * A077448 A085986 A027603
KEYWORD
nonn
AUTHOR
EXTENSIONS
Definition corrected - R. J. Mathar, Dec 06 2010
STATUS
approved

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Last modified March 29 11:44 EDT 2024. Contains 371278 sequences. (Running on oeis4.)