cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A172443 Numbers with exactly 64 divisors.

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%I A172443 #23 Aug 28 2021 04:57:53
%S A172443 7560,9240,10920,11880,13440,14040,14280,15960,16632,17160,17280,
%T A172443 18360,19320,19656,20520,20790,21000,21120,22440,24024,24192,24360,
%U A172443 24570,24840,24960,25080,25704,26040,26520,27000,28728,29568,29640,30030,30360,30888,31080
%N A172443 Numbers with exactly 64 divisors.
%C A172443 The first squarefree term of this sequence is the primorial a(34) = 30030.
%C A172443 Almost all terms of this sequence (in the sense of having relative density 1) are squarefree, that is in our case, the product of six distinct primes = A067885. - _Charles R Greathouse IV_, Aug 27 2021
%H A172443 David A. Corneth, <a href="/A172443/b172443.txt">Table of n, a(n) for n = 1..10000</a>
%e A172443 10920 has 64 divisors.
%t A172443 Select[Range[100000],DivisorSigma[0,#]==64&]
%o A172443 (PARI) is(n) = numdiv(n) == 64 \\ _David A. Corneth_, Aug 27 2021
%o A172443 (Python)
%o A172443 from sympy import divisor_count
%o A172443 def ok(n): return divisor_count(n) == 64
%o A172443 print(list(filter(ok, range(31100)))) # _Michael S. Branicky_, Aug 27 2021
%Y A172443 Cf. A067885.
%K A172443 nonn,easy
%O A172443 1,1
%A A172443 _Harvey P. Dale_, Nov 20 2010