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A343725
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a(n) is the largest n-digit square with all digits even.
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3
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4, 64, 484, 8464, 88804, 868624, 8880400, 86862400, 888040000, 8880800644, 88864802404, 888868068804, 8886826042084, 88886806880400, 888686062262244, 8888680688040000, 88868606226224400, 888868068804000000, 8888600480200862404, 88886806880400000000
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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LINKS
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PROG
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(Python 3.8+)
from math import isqrt
m = isqrt(8*(10**i-1)//9)
m -= m % 2
k = m**2
s = set('02468')
while not set(str(k)) <= s:
m -= 2
k -= 4*(m+1)
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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