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A054039
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a(n)^2 is the least square to contain n different decimal digits.
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13
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OFFSET
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1,2
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COMMENTS
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It turns out that "...at least n..." and "...exactly n..." yield the same (and thus strictly increasing) sequence. - M. F. Hasler, Feb 02 2009
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LINKS
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EXAMPLE
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13^2=169 is the first square to contain exactly 3 different digits; 322^2=103684 is the first square to contain exactly 6 different digits.
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PROG
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(PARI) A054039(n, k=0) = { while( #Set(Vec(Str(k^2)))<n, k++); k } /* If "exactly n" would correspond to a different sequence, this would yield some term twice in a row. The optional 2nd arg can be used to find further terms with a given # of distinct digits. - M. F. Hasler, Feb 02 2009 */
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CROSSREFS
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KEYWORD
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nonn,fini,full,base,easy
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AUTHOR
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EXTENSIONS
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Minor rewording, added comment, keywords "easy,full" and PARI code M. F. Hasler, Feb 02 2009
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STATUS
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approved
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