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A272680
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Smallest square that begins with n (in binary).
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3
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0, 1, 4, 25, 4, 81, 25, 121, 16, 9, 81, 361, 25, 441, 225, 121, 16, 1089, 36, 625, 81, 169, 361, 1521, 49, 25, 841, 441, 225, 3721, 121, 2025, 64, 529, 1089, 4489, 36, 2401, 1225, 625, 81, 5329, 169, 2809, 11449, 361, 5929, 1521, 6241, 49, 100, 6561, 841, 6889
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,3
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REFERENCES
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Allan C. Wechsler, posting to math-fun mailing list May 22 2016.
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LINKS
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EXAMPLE
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a(10)=81, because 81 = 9^2 = 1010001_2 begins with 1010 = 10_2.
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PROG
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(Python)
from gmpy2 import isqrt
if n == 0:
return 0
else:
d, nd = 1, n
while True:
x = (isqrt(nd-1)+1)**2
if x < nd+d:
return int(x)
d *= 2
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CROSSREFS
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KEYWORD
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nonn,base,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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