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A036493 Largest number having binary order n (A029837) and of which the number of divisors is maximal in that range of g(k) = n. 2

%I #25 May 16 2018 10:15:14

%S 1,2,4,8,12,30,60,120,240,504,840,1680,3960,7560,15120,32760,65520,

%T 131040,262080,498960,997920,1965600,3603600,7207200,14414400,

%U 32432400,64864800,122522400,245044800,514594080,1029188160,2095133040,4227022800,8454045600

%N Largest number having binary order n (A029837) and of which the number of divisors is maximal in that range of g(k) = n.

%C This sequence differs from A036451 only at n = 3, 5, 9, 12, and 15, which are the values of n for which there exists more than one k such that g(k) = n and d(k) has the maximum possible value.

%C a(n) is the largest term k in A067128 such that log_2(k) <= n. - _Jon E. Schoenfield_, May 13 2018

%e For n = 9, k is in {257, 512}, max(d(k)) = 24 (see A036451); this holds for four different numbers (360, 420, 480, and 504); a(9) = 504 since it is the largest.

%t {1}~Join~Table[Max@ MaximalBy[Range[2^(n - 1) + 1, 2^n], DivisorSigma[0, #] &], {n, 24}] (* _Michael De Vlieger_, Aug 01 2017 *)

%Y Cf. A000005, A029837, A005179, A007416, A036451, A036470, A036484.

%K nonn

%O 0,2

%A _Labos Elemer_

%E a(22)-a(24) from _Michael De Vlieger_, Aug 01 2017

%E a(25)-a(33) from _Jon E. Schoenfield_, May 12 2018

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Last modified April 25 03:15 EDT 2024. Contains 371964 sequences. (Running on oeis4.)