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A075415
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Squares of A002280 or numbers (666...6)^2.
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27
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0, 36, 4356, 443556, 44435556, 4444355556, 444443555556, 44444435555556, 4444444355555556, 444444443555555556, 44444444435555555556, 4444444444355555555556, 444444444443555555555556, 44444444444435555555555556, 4444444444444355555555555556
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OFFSET
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0,2
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COMMENTS
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A transformation of the Wonderful Demlo numbers (A002477).
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LINKS
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FORMULA
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a(n) = (6*(10^n-1)/9)^2 = (4/9)*(10^(2*n) - 2*10^n + 1), which is n-1 4's, followed by a 3, n-1 5's and a 6. - Ignacio Larrosa Cañestro, Feb 26 2005
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EXAMPLE
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a(2) = 66^2 = 4356.
n=1: ..................... 36 = 9 * 4;
n=2: ................... 4356 = 99 * 44;
n=3: ................. 443556 = 999 * 444;
n=4: ............... 44435556 = 9999 * 4444;
n=5: ............. 4444355556 = 99999 * 44444;
n=6: ........... 444443555556 = 999999 * 444444;
n=7: ......... 44444435555556 = 9999999 * 4444444;
n=8: ....... 4444444355555556 = 99999999 * 44444444;
n=9: ..... 444444443555555556 = 999999999 * 444444444. (End)
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MATHEMATICA
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Table[FromDigits[PadRight[{}, n, 6]]^2, {n, 0, 20}] (* or *) LinearRecurrence[ {111, -1110, 1000}, {0, 36, 4356}, 20] (* Harvey P. Dale, May 20 2021 *)
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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Michael Taylor (michael.taylor(AT)vf.vodafone.co.uk), Sep 14 2002
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EXTENSIONS
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Edited by Alois P. Heinz, Aug 21 2019 (merged with A102794, submitted by Richard C. Schroeppel, Feb 26 2005)
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STATUS
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approved
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