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A061457
Squares whose reversal is also a square.
11
0, 1, 4, 9, 100, 121, 144, 169, 400, 441, 484, 676, 900, 961, 1089, 9801, 10000, 10201, 10404, 10609, 12100, 12321, 12544, 12769, 14400, 14641, 14884, 16900, 40000, 40401, 40804, 44100, 44521, 44944, 48400, 48841, 67600, 69696, 90000, 90601
OFFSET
1,3
COMMENTS
The corresponding square roots are in A102859.
LINKS
FORMULA
a(n) = A102859(n)^2.
EXAMPLE
169 and 961 are both squares.
1089 = 33^2 and 9801 = 99^2 so 1089 and 9801 belong to the sequence.
MATHEMATICA
Select[Range[0, 400]^2, IntegerQ[Sqrt[IntegerReverse[#]]]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jul 29 2019 *)
PROG
(PARI) { for(m=0, 1000, my(r=fromdigits(Vecrev(digits(m^2)))); if(issquare(r), print1(m^2, ", ") )) } \\ Harry J. Smith, Jul 23 2009
(Magma) [n^2: n in [0..306] | IsSquare(Seqint(Reverse(Intseq(n^2))))]; // Bruno Berselli, Apr 30 2011
(Python)
from itertools import count, islice
from sympy import integer_nthroot
def A061457_gen(): # generator of terms
return filter(lambda n:integer_nthroot(int(str(n)[::-1]), 2)[1], (n**2 for n in count(0)))
A061457_list = list(islice(A061457_gen(), 30)) # Chai Wah Wu, Nov 18 2022
CROSSREFS
Cf. A102859 (square roots), A033294 (exclude final digit 0).
Sequence in context: A245241 A115690 A115689 * A069707 A129967 A182020
KEYWORD
nonn,base,easy
AUTHOR
Amarnath Murthy, May 03 2001
EXTENSIONS
More terms from Larry Reeves (larryr(AT)acm.org), May 17 2001
STATUS
approved