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A178634
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63 * ((10^n - 1)/9)^2.
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12
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63, 7623, 776223, 77762223, 7777622223, 777776222223, 77777762222223, 7777777622222223, 777777776222222223, 77777777762222222223, 7777777777622222222223, 777777777776222222222223
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OFFSET
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1,1
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COMMENTS
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a(n) = 63*A002477(n) = A002283(n)*A002281(n).
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REFERENCES
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Walther Lietzmann, Lustiges und Merkwuerdiges von Zahlen und Formen, (F. Hirt, Breslau 1921-43), p. 149.
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LINKS
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Table of n, a(n) for n=1..12.
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FORMULA
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a(n)=((A002281(n-1)*10+6)*10^(n-1)+A002276(n-1))*10+3.
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EXAMPLE
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n=1: ..................... 63 = 9 * 7;
n=2: ................... 7623 = 99 * 77;
n=3: ................. 776223 = 999 * 777;
n=4: ............... 77762223 = 9999 * 7777;
n=5: ............. 7777622223 = 99999 * 77777;
n=6: ........... 777776222223 = 999999 * 777777;
n=7: ......... 77777762222223 = 9999999 * 7777777;
n=8: ....... 7777777622222223 = 99999999 * 77777777;
n=9: ..... 777777776222222223 = 999999999 * 777777777.
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MATHEMATICA
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63((10^Range[15]-1)/9)^2 (* or *) Table[FromDigits[Join[PadRight[{}, n, 7], {6}, PadRight[{}, n, 2], {3}]], {n, 0, 15}] (* From Harvey P. Dale, Apr 23 2012 *)
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PROG
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(MAGMA)[63*((10^n - 1)/9)^2: n in [1..50]]; [From V. Librandi, Dec 28 2010]
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CROSSREFS
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Cf. A075412, A178630, A178631, A075415, A178632, A178633, A178635, A059988.
Sequence in context: A046190 A093263 A069433 * A174763 A160871 A183525
Adjacent sequences: A178631 A178632 A178633 * A178635 A178636 A178637
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KEYWORD
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nonn
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AUTHOR
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Reinhard Zumkeller, May 31 2010
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STATUS
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approved
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