OFFSET
1,3
COMMENTS
Every power of 10 is a term in the sequence.
If k is in the sequence then so is 10*k. - David A. Corneth, Aug 06 2022
If all multiples of 10 were omitted, A074896 would result. - Jon E. Schoenfield, Aug 06 2022
EXAMPLE
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).
MATHEMATICA
Select[Range[0, 1500], IntegerQ[Sqrt[IntegerReverse[#]]] &] (* Amiram Eldar, Aug 06 2022 *)
PROG
(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)
(PARI) isok(k) = issquare(fromdigits(Vecrev(digits(k)))); \\ Michel Marcus, Aug 06 2022
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Daniel Blam, Aug 06 2022
STATUS
approved