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A034822
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Numbers k such that there are no palindromic squares of length k.
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12
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2, 4, 8, 10, 14, 18, 20, 24, 30, 38, 40
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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COMMENTS
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All terms are even since (10^k+1)^2 is a palindrome of length 2*k+1. a(12) >= 46 if it exists (see A263618). - Chai Wah Wu, Jun 14 2024
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LINKS
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MATHEMATICA
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A034822[n_] := Select[Range[Ceiling[Sqrt[10^(n - 1)]], Floor[Sqrt[10^n]]], #^2 == IntegerReverse[#^2] &];
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PROG
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(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
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CROSSREFS
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KEYWORD
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nonn,base,hard,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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