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.

A260402 Numbers which cannot be the largest denominator of an Egyptian fraction for 1.

This page as a plain text file.
%I A260402 #26 Jun 22 2025 06:30:26
%S A260402 2,3,4,5,7,8,9,10,11,13,14,16,17,19,21,22,23,25,26,27,29,31,32,34,37,
%T A260402 38,39,41,43,44,46,47,49,50,51,53,57,58,59,61,62,64,67,68,69,71,73,74,
%U A260402 79,81,82,83,86,87,89,92,93,94,97,98,101,103,106,107,109
%N A260402 Numbers which cannot be the largest denominator of an Egyptian fraction for 1.
%C A260402 Complement of A092671.
%C A260402 Contains at all primes and prime powers (A000961).
%C A260402 Martin studies the asymptotic behavior of this sequence: the order of magnitude of its counting function (number of elements below x) is x log log x / log x.
%H A260402 Amiram Eldar, <a href="/A260402/b260402.txt">Table of n, a(n) for n = 1..5000</a>
%H A260402 Greg Martin, <a href="http://matwbn.icm.edu.pl/ksiazki/aa/aa95/aa9533.pdf">Denser Egyptian fractions</a>, Acta Arith. 95 (2000), no. 3, 231-260.
%H A260402 Greg Martin, <a href="http://www.math.ubc.ca/~gerg/slides/Urbana-27March09.pdf">Dense Egyptian fractions</a>, Talk at the AMS Spring Central Sectional Meeting, University of Illinois at Urbana-Champaign, March 27, 2009.
%e A260402 10 is in this sequence because any Egyptian fraction with 1/10 as its term with largest denominator either contains 1/5 as well or not; either way, the resulting sum will have a factor 5 in its denominator (any other term will contribute a multiple of 5 to the numerator of the sum), hence cannot equal 1.
%K A260402 nonn
%O A260402 1,1
%A A260402 _M. F. Hasler_, Jul 24 2015