A099502 - OEIS

%I #13 Feb 26 2018 09:31:31

%S 3,13,20,78,85,92,99,109,136,139,143,146,150,358,402,440,457,477,501,

%T 546,549,583,611,638,655,665,696,730,754,778,812,887,904,966,979,996,

%U 1034,1051,2089,2161,2427,2458,2499,2697,2751,2813,2840,2912,2922,2929

%N Numbers n such that A099501(n) = 3.

%C Granville and Selfridge discuss the numbers n+1 in their paper. For each of these n<10000, Scott Contini found three integers between n^2 and (n+1)^2 such that their product is twice a square. There are 123 instances of n < 10000; 215 instances for n < 20000.

%H Donovan Johnson and Giovanni Resta, <a href="/A099502/b099502.txt">Table of n, a(n) for n = 1..516</a> (terms < 10^5, first 367 terms from Donovan Johnson)

%H Andrew Granville and John Selfridge, <a href="http://www.combinatorics.org/ojs/index.php/eljc/article/view/v8i1r5">Product of integers in an interval, modulo squares</a>, Electronic Journal of Combinatorics, Volume 8(1), 2001.

%H Giovanni Resta, <a href="/A099502/a099502.txt">Table of n, a(n), x, y, z, where x, y, z is the triple corresponding to a(n)<10^5</a>

%e 13 is here because {171,180,190} is the smallest set of integers in the interval [170,195] whose product is twice a square.

%Y Cf. A099500 (number of subsets), A099501 (size of the subset having the least number of integers).

%K hard,nonn

%O 1,1

%A _T. D. Noe_, Oct 20 2004