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A359245
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The smallest square with exactly n circular loops (or holes) in its decimal expansion (A064532).
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0
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1, 0, 81, 289, 1089, 8836, 6889, 80089, 688900, 1868689, 8508889, 29888089, 288898009, 983888689, 3808988089, 8680089889, 86908808809, 488088068689, 878686888689, 2888986888804, 48890888808804, 108506888888896, 88869893888889, 880881089888881, 788088668888889
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OFFSET
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0,3
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COMMENTS
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The digit 8 has two loops, the digits 0, 6 and 9 have one loop, and other digits (including 4) have no hole.
Least square k such that A064532(k) = n.
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LINKS
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EXAMPLE
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a(3) = 289 because 8 has two loops and 9 has one loop for a total of 3, and 289 is the smallest such square.
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PROG
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(PARI) a(n) = { for (k=0, oo, my (d=digits(k^2)); if (n==(k==0)+sum(i=1, #d, [1, 0, 0, 0, 0, 0, 1, 0, 2, 1][1+d[i]]), return (k^2))) } \\ Rémy Sigrist, Dec 22 2022
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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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EXTENSIONS
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STATUS
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approved
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