A356417 Numbers whose reversal is a square.
0, 1, 4, 9, 10, 18, 40, 46, 52, 61, 63, 90, 94, 100, 121, 144, 148, 163, 169, 180, 400, 423, 441, 460, 484, 487, 520, 522, 526, 610, 630, 652, 675, 676, 691, 900, 925, 927, 940, 961, 982, 1000, 1042, 1062, 1089, 1210, 1251, 1273, 1297, 1405, 1426, 1440, 1480
Offset: 1
Examples
0 is a term, 0 -> 0 (0^2). 10 is a term, 10 -> 01 (leading zero is dropped) (1^2). 691 is a term, 691 -> 196 (14^2). 1800 is a term, 1800 -> 0081 (leading zeros are dropped) (9^2).
Programs
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Mathematica
Select[Range[0, 1500], IntegerQ[Sqrt[IntegerReverse[#]]] &] (* Amiram Eldar, Aug 06 2022 *)
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PARI
isok(k) = issquare(fromdigits(Vecrev(digits(k)))); \\ Michel Marcus, Aug 06 2022
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Python
from sympy import integer_nthroot def ok(n): return integer_nthroot(int(str(n)[::-1]), 2)[1] print([k for k in range(1500) if ok(k)]) -
Python
from math import isqrt from itertools import count, islice def A356417_gen(): # generator of terms yield 0 for l in count(1): nlist = [] for m in range(1,isqrt(10**l)+1): if m%10: s = str(m**2) nlist.append(int(s[::-1])*10**(l-len(s))) yield from sorted(nlist) A356417_list = list(islice(A356417_gen(),100)) # Chai Wah Wu, Aug 07 2022
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