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A088036 Numbers k such that k^3 - 1 is divisible by a cube other than 1. 2

%I #18 Sep 10 2021 10:49:11

%S 9,10,17,18,19,25,28,33,37,41,46,49,55,57,64,65,73,81,82,89,91,97,100,

%T 105,109,113,118,121,126,127,129,136,137,145,153,154,161,163,169,172,

%U 177,181,185,190,193,199,201,208,209,217,225,226,233,235,241,244,249

%N Numbers k such that k^3 - 1 is divisible by a cube other than 1.

%H R. J. Mathar, <a href="/A088036/b088036.txt">Table of n, a(n) for n = 1..1185</a>

%p isA046099 := proc(n)

%p local p;

%p for p in ifactors(n)[2] do

%p if op(2,p) >= 3 then

%p return true;

%p end if;

%p end do:

%p false ;

%p end proc:

%p n := 1;

%p for i from 1 to 5000 do

%p if isA046099(i^3-1) then

%p printf("%d %d\n",n,i) ;

%p n := n+1;

%p end if;

%p end do: # _R. J. Mathar_, Dec 03 2015

%t n3dcQ[n_]:=Count[Divisors[n^3-1]],_?(IntegerQ[Surd[#,3]]&)>1; Select[ Range[ 2,250],n3dcQ] (* _Harvey P. Dale_, Oct 05 2017 *)

%o (Python)

%o from sympy import factorint

%o def ok(n): return max(factorint(n**3 - 1).values()) >= 3

%o print(list(filter(ok, range(1, 250)))) # _Michael S. Branicky_, Sep 10 2021

%Y Cf. A068601, A088035.

%K nonn

%O 1,1

%A _Amarnath Murthy_, Sep 19 2003

%E Corrected and extended by _Ray Chandler_, Sep 23 2003

%E Definition clarified by _Harvey P. Dale_, Oct 05 2017

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Last modified September 1 18:06 EDT 2024. Contains 375593 sequences. (Running on oeis4.)