OFFSET
1,1
FORMULA
a(k) = 2*k^2 for k not in A009003.
PROG
(Python)
from sympy.solvers.diophantine.diophantine import diop_DN
def A356209(n):
for m in range(n**2<<1, 0, -1):
if n==max((a for a, b in diop_DN(-1, m)), default=0):
return m # Chai Wah Wu, Sep 08 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
Hugo Pfoertner, Sep 07 2022
STATUS
approved