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.

A046971 Maximal value of number of unitary divisors (see A034444) for integers in binary order range of n.

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%I A046971 #17 Apr 28 2019 05:36:12
%S A046971 2,2,4,4,8,8,8,16,16,16,16,32,32,32,64,64,64,64,128,128,128,128,128,
%T A046971 256,256,256,256,512,512,512,512,512,1024,1024,1024,1024,1024,2048,
%U A046971 2048,2048,2048,2048,4096,4096,4096,4096,4096,4096,8192,8192,8192,8192
%N A046971 Maximal value of number of unitary divisors (see A034444) for integers in binary order range of n.
%C A046971 Q_k the k-th primorial number (A002110) is the smallest positive integer whose number of unitary divisors (A034444) is 2^k. Thus the binary orders (A029837) of primorial numbers (A045716) determine the maximal values of unitary divisors in binary order ranges.
%H A046971 Charles R Greathouse IV, <a href="/A046971/b046971.txt">Table of n, a(n) for n = 1..10000</a>
%H A046971 <a href="/index/Di#divseq">Index to divisibility sequences</a>
%F A046971 2^k occurs in the sequence g(Q_k) - g(Q_k-1)+1 times, where g is the binary order and Q_k is the k-th primorial number.
%e A046971 128 occurs in the sequence from index 19 and 23 inclusively (5 times) because the 7th primorial number Q_7=510510 has binary order 19 and Q_8, the next one is 9699690 has binary order 24 (it is between 2^23 and 2^24).
%o A046971 (PARI) v=List([2]);n=0;P=p=2;forprime(q=3,97, n++;for(i=1, log(P*q)\log(2)-log(P)\log(2), listput(v,1<<n));P*=p=q);Vec(v) \\ _Charles R Greathouse IV_, Apr 08 2012
%Y A046971 Cf. A002110, A029837, A034444, A045716.
%K A046971 nonn
%O A046971 1,1
%A A046971 _Labos Elemer_