A358880 Squares of the form k + reverse(k) for at least one k.

4, 16, 121, 484, 625, 1089, 10201, 14641, 19881, 40804, 49284, 69696, 91809, 94249, 203401, 698896, 1002001, 1234321, 1490841, 1517824, 4008004, 4276624, 4460544, 4937284, 5313025, 6325225, 6895876, 6948496, 7706176, 9018009, 15665764, 15776784, 16120225

Offset: 1

Author

Jon E. Schoenfield, Dec 04 2022

Keywords

• nonn
• base

Examples

			56 + reverse(56) = 56 + 65 = 121 = 11^2, so 121 is a term.
		

Crossrefs

Cf. A000290, A067030, A356648.

Programs

Python

from math import isqrt
def aupto(lim): return sorted(set(t for t in (k + int(str(k)[::-1]) for k in range(1, lim+1)) if t <= lim and isqrt(t)**2 == t))
print(aupto(10**7)) # Michael S. Branicky, Dec 25 2022

Formula

a(n) = A356648(n)^2. - Michel Marcus, Dec 25 2022