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A110460
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Least multiple of n such that every concatenation a(1)...a(i) for 1 <= i <= n is a perfect square.
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0
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1, 6, 9, 744, 4179600, 8448511339584, 5768007101259200000000000049, 5174534068654382362457957919012519218990703784333328400, 2738806678866818978778889262772030983678218158753649709561749318814684327986697592167893627634348717226004356
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OFFSET
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1,2
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LINKS
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EXAMPLE
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1, 16, 169, 169744 are all squares. [corrected by Harvey P. Dale, Aug 06 2019]
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PROG
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(PARI) f(n, num) = local(d, x); d = 1; while (1, x = sqrtint(num*10^d + 10^(d - 1) - 1) + 1; while (x^2 < (num + 1)*10^d && (x^2%10^d)%n, x++); if (x^2 < (num + 1)*10^d, return([x^2, x^2%10^d])); d++);
num = 0; for (n = 1, 10, p = f(n, num); print1(p[2], ", "); num = p[1]); \\ David Wasserman, Dec 03 2008
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CROSSREFS
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KEYWORD
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base,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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