OFFSET
1,1
COMMENTS
Sequence is complement of A372477.
This sequence consists of the positive integers that cannot be represented in the form (n*n + k*k - k*n, n*n + k*k - k*n + k - n), n > 0, 0 <= k < n.
LINKS
Yury Kazakov, Table of n, a(n) for n = 1..1000
N. A. Shikhova, Discussion of a problem on the social network VK (in Russian).
N. A. Shikhova, Illustration for the sequence A372477.
PROG
(Python)
import math
L=20 #tr are terms A372477 below L**2+1
numb=set()
Lmax=math.trunc((1+2*math.sqrt(3*L**2+1))/3)+1
tr=set()
tr.add(1)
for n in range(2, Lmax):
for k in range(0, n):
p1=n*n+k*k-k*n
p2=p1+k-n
if p1<=L**2:
tr.add(p1)
if p2<=L**2:
tr.add(p2)
for k in range (1, L**2):
numb.add(k)
print(sorted(numb-tr))
CROSSREFS
KEYWORD
nonn
AUTHOR
Yury Kazakov, S. P. Obukhov, Sean Sun, and N. A. Shikhova, May 03 2024
STATUS
approved