cp's OEIS Frontend

A371721 Numbers representable in the form u*v*(u+v) for u >= v >= 0 in at least two ways.

%I A371721 #11 Dec 16 2024 02:09:35
%S A371721 0,30,210,240,390,420,462,810,880,1008,1020,1056,1122,1190,1482,1680,
%T A371721 1920,1980,2070,2100,2310,2970,3120,3360,3696,3750,4160,4290,4320,
%U A371721 4830,4914,5460,5670,6006,6090,6270,6480,6630,7040,7380,7440,7770,8064,8160,8190,8448,8580,8976,9120,9240,9520,9900,10290,10530,10640,11340,11856,12210,12432,12474,13110
%N A371721 Numbers representable in the form u*v*(u+v) for u >= v >= 0 in at least two ways.
%H A371721 Robert Israel, <a href="/A371721/b371721.txt">Table of n, a(n) for n = 1..10000</a>
%p A371721 N:= 10^5: # for terms <= N
%p A371721 V:= Vector(N):
%p A371721 for v from 1 while 2*v^3 <= N do
%p A371721   for u from v do
%p A371721     x:= u*v*(u+v);
%p A371721     if x > N then break fi;
%p A371721     V[x]:= V[x]+1
%p A371721 od od:
%p A371721 [0,op(select(t -> V[t] >= 2, [$1..N]))]; # _Robert Israel_, Dec 15 2024
%Y A371721 Subsequence of A088915.
%Y A371721 Cf. A369333, A369334.
%K A371721 nonn
%O A371721 1,2
%A A371721 _Max Alekseyev_, Apr 04 2024