|
%I #11 Jan 14 2020 22:15:53
%S 216,1000,2744,3375,9261,10648,17576,27000,35937,39304,42875,54872,
%T 59319,74088,97336,132651,166375,185193,195112,238328,274625,287496,
%U 328509,343000,405224,456533,474552,551368,614125,636056,658503,753571,804357,830584,857375
%N Products of cubes of 2 or more distinct primes.
%H Andrew Howroyd, <a href="/A177493/b177493.txt">Table of n, a(n) for n = 1..1000</a>
%F a(n) = A120944(n)^3. - _R. J. Mathar_, Dec 06 2010
%e 216 = 2^3 * 3^3.
%e 9261 = 3^3 * 7^3.
%e 27000 = 2^3 * 3^3 * 5^3.
%t f1[n_]:=Length[Last/@FactorInteger[n]]; f2[n_]:=Union[Last/@FactorInteger[n]]; lst={};Do[If[f1[n]>1&&f2[n]=={3},AppendTo[lst,n]],{n,0,9!}];lst
%t Reap[Do[{p, e}=Transpose[FactorInteger[n]]; If[Length[p]>1 && Union[e]=={3}, Sow[n]], {n, 343000}]][[2, 1]]
%o (PARI) [k^3 | k<-[1..100], k>1 && !isprime(k) && issquarefree(k)] \\ _Andrew Howroyd_, Jan 14 2020
%Y Cf. A000469, A085986, A162142, A177492.
%K nonn
%O 1,1
%A _Vladimir Joseph Stephan Orlovsky_, May 10 2010
%E Definition corrected by _R. J. Mathar_, Dec 06 2010
%E Terms a(25) and beyond from _Andrew Howroyd_, Jan 14 2020
|
