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A034822 Numbers n such that there are no palindromic squares of length n. 11
2, 4, 8, 10, 14, 18, 20, 24, 30, 38, 40 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
Patrick De Geest, Palindromic Squares
Eric Weisstein's World of Mathematics, Palindromic Number
MATHEMATICA
A034822[n_] := Select[Range[Ceiling[Sqrt[10^(n - 1)]], Floor[Sqrt[10^n]]], #^2 == IntegerReverse[#^2] &];
Select[Range[12], Length[A034822[#]] == 0 &] (* Robert Price, Apr 23 2019 *)
PROG
(Python)
from sympy import integer_nthroot as iroot
def ispal(n): s = str(n); return s == s[::-1]
def ok(n):
for r in range(iroot(10**(n-1), 2)[0] + 1, iroot(10**n, 2)[0]):
if ispal(r*r): return False
return True
print([m for m in range(1, 16) if ok(m)]) # Michael S. Branicky, Feb 04 2021
CROSSREFS
Sequence in context: A189670 A341822 A363797 * A300781 A050567 A069879
KEYWORD
nonn,base,hard,more
AUTHOR
Patrick De Geest, Oct 15 1998
EXTENSIONS
Two more terms from Patrick De Geest, Apr 01 2002
STATUS
approved

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Last modified March 28 08:00 EDT 2024. Contains 371235 sequences. (Running on oeis4.)