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A364168
Numbers that can be written in more than one way in the form (j+2k)^2-(j+k)^2-j^2 with j,k>0.
0
15, 27, 32, 35, 36, 39, 51, 55, 60, 63, 64, 75, 84, 87, 91, 95, 96, 99, 100, 108, 111, 115, 119, 123, 128, 132, 135, 140, 143, 144, 147, 155, 156, 159, 160, 171, 175, 180, 183, 187, 192, 195, 196, 203, 204, 207, 215, 219, 220, 224, 228, 231, 235, 240, 243, 247, 252, 255
OFFSET
1,1
EXAMPLE
27 is a term since (6+2*3)^2 - (6+3)^2 - 6^2 = (20+2*7)^2 - (20+7)^2 - 20^2 = 27.
PROG
(Python)
from sympy import divisors
def isok(n):
s = 0
for d in divisors(n):
t = n // d + d
if ((q:=t >> 2) << 2) == t and q < d:
s += 1
return s > 1
print([n for n in range(1, 256) if isok(n)])
CROSSREFS
KEYWORD
nonn
AUTHOR
Darío Clavijo, Jul 12 2023
STATUS
approved