|
|
A332770
|
|
a(n) is the number of ways to write A180045(n) as (x*y+1)*(x*z+1) with x > y > z > 1.
|
|
2
|
|
|
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 3, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 1, 2, 1, 1, 2
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,13
|
|
LINKS
|
|
|
EXAMPLE
|
The first terms, alongside A180045(n), are:
-- ---- ---------------------------------------
1 1 28 = (3*2+1)*(3*1+1)
2 1 45 = (4*2+1)*(4*1+1)
3 1 65 = (4*3+1)*(4*1+1)
4 1 66 = (5*2+1)*(5*1+1)
5 1 91 = (6*2+1)*(6*1+1)
6 1 96 = (5*3+1)*(5*1+1)
7 1 117 = (4*3+1)*(4*2+1)
8 1 120 = (7*2+1)*(7*1+1)
9 1 126 = (5*4+1)*(5*1+1)
10 1 133 = (6*3+1)*(6*1+1)
11 1 153 = (8*2+1)*(8*1+1)
12 1 175 = (6*4+1)*(6*1+1)
13 2 176 = (5*3+1)*(5*2+1) = (7*3+1)*(7*1+1)
|
|
MAPLE
|
N:= 20000: # for a(n) where A180045(n) <= N
V:= Vector(N):
for x from 3 while (2*x+1)*(x+1) <= N do
for y from 2 to x-1 while (x*y+1)*(x+1) <= N do
for z from 1 to y-1 do
v:= (x*y+1)*(x*z+1);
if v > N then break fi;
V[v]:= V[v]+1;
od od od:
|
|
PROG
|
(C) See Links section.
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|