A356209 a(n) is the position of the latest occurrence of n in A133388.
2, 8, 18, 32, 41, 72, 98, 128, 162, 181, 242, 288, 313, 392, 421, 512, 514, 648, 722, 761, 882, 968, 1058, 1152, 1201, 1301, 1458, 1568, 1466, 1741, 1922, 2048, 2178, 2056, 2381, 2592, 2594, 2888, 2817, 3121, 3202, 3528, 3698, 3872, 3789, 4232, 4418, 4608, 4802, 4804, 5101
Offset: 1
Keywords
Programs
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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
Formula
a(k) = 2*k^2 for k not in A009003.