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A192934
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Smallest square number starting with (at least) n identical digits.
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2
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1, 225, 22201, 5555449, 111112681, 3333330225, 555555566736, 2222222266944, 33333333393562596, 88888888888905609, 88888888888905609, 2222222222222640225, 2222222222222640225, 111111111111119590793871025, 5555555555555557064110500049, 11111111111111115805344390916
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OFFSET
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1,2
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COMMENTS
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Conjecture: total number of digits of a(n) is always 2*n-1.
This conjecture is false: length(a(6)) = 10 != 2*6-1 = 11.
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LINKS
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FORMULA
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EXAMPLE
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a(2) = 225 because none of 11, 22, 33, 44, 55, 66, 77, 88, 99, any integer from 110 to 119, or any integer from 220 to 224 is a square, but 15^2 = 225.
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PROG
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(PARI) a(n) = {if (n == 1, return (1)); ok = 0; i = 1; while (! ok, i++; d = digits(i^2, 10); if (#d >= n, ok = 1; for (k = 2, n, if (d[k] != d[1], ok = 0; break; ); ); ); ); return (i^2); } \\ Michel Marcus, Jun 14 2013
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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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