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.

A045716 a(n) is the binary order (A029837) of the n-th primorial number, A002110(n).

This page as a plain text file.
%I A045716 #21 Jun 18 2018 04:13:59
%S A045716 1,3,5,8,12,15,19,24,28,33,38,43,49,54,60,65,71,77,83,89,96,102,108,
%T A045716 115,121,128,135,141,148,155,162,169,176,183,190,198,205,212,220,227,
%U A045716 235,242,250,257,265,273,280,288,296,304,312,319,327,335,343,351,359
%N A045716 a(n) is the binary order (A029837) of the n-th primorial number, A002110(n).
%C A045716 These orders determine the maximal numbers of unitary divisors valid for integers in given binary order ranges (see A046971).
%H A045716 Michael De Vlieger, <a href="/A045716/b045716.txt">Table of n, a(n) for n = 1..10000</a>
%F A045716 a(n) = A054850(n)+1, n >= 2.
%F A045716 a(n) = A070939(A002110(n)) for n>1. - _Jachym Barvinek_, Mar 22 2018
%e A045716 The sixth primorial number is 2*3*5*7*11*13 = 30030, which is in the interval [16385, 32768] = [2^14 + 1, 2^15], so its binary order is a(6)=15. [corrected by _Jon E. Schoenfield_, May 13 2018]
%t A045716 Table[Ceiling@ Log2[Times @@ Prime@ Range@ n], {n, 57}] (* _Michael De Vlieger_, Feb 05 2017 *)
%o A045716 (PARI) a(n)=logint(prod(i=1,n,prime(i))-1,2)+1 \\ _Charles R Greathouse IV_, Feb 06 2017
%Y A045716 Cf. A029837, A002110, A046971, A054850.
%K A045716 nonn
%O A045716 1,2
%A A045716 _Labos Elemer_