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Rotating digits of a(n)^2 right once still yields a square.
4

%I #22 Apr 23 2022 19:17:04

%S 1,2,3,16,21,31,129,221,247,258,1062,1593,1964,2221,13516,17287,18516,

%T 19821,22221,28064,29631,103764,182362,222221,273543,1246713,1509437,

%U 1635219,1856538,2222221,2253804,2749249,2784807,11619096,11949507

%N Rotating digits of a(n)^2 right once still yields a square.

%C Squares resulting in leading zeros excluded.

%C (2*10^k-11)/9 are terms, i.e. A165402 is a subsequence. - _Chai Wah Wu_, Apr 23 2022

%H Chai Wah Wu, <a href="/A045877/b045877.txt">Table of n, a(n) for n = 1..1838</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/SquareNumber.html">Square Number</a>

%e 13516^2 = 18268225{6} -> {6}18268225 = 24865^2.

%o (Python)

%o from itertools import count, islice

%o from sympy.solvers.diophantine.diophantine import diop_DN

%o def A045877_gen(): # generator of terms

%o for l in count(0):

%o l1, l2 = 10**(l+1), 10**l

%o yield from sorted(set(abs(x) for z in (diop_DN(10,m*(1-l1)) for m in range(10)) for x, y in z if l1 >= x**2 >= l2))

%o A045877_list = list(islice(A045877_gen(),30)) # _Chai Wah Wu_, Apr 23 2022

%Y Cf. A000290, A045878, A035126, A035128, A165402.

%K nonn,base

%O 1,2

%A _Erich Friedman_

%E More terms from _Patrick De Geest_, Nov 15 1998