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A001744
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Numbers n such that every digit contains a loop (version 2).
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18
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0, 4, 6, 8, 9, 40, 44, 46, 48, 49, 60, 64, 66, 68, 69, 80, 84, 86, 88, 89, 90, 94, 96, 98, 99, 400, 404, 406, 408, 409, 440, 444, 446, 448, 449, 460, 464, 466, 468, 469, 480, 484, 486, 488, 489, 490, 494, 496, 498, 499, 600, 604, 606, 608, 609, 640, 644, 646
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OFFSET
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1,2
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COMMENTS
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See A001743 for the other version.
If n-1 is represented as a base-5 number (s. A007091) according to n-1 = d(m)d(m-1)…d(3)d(2)d(1)d(0) then a(n)= sum_{j=0..m} c(d(j))*10^j, where c(k)=0,4,6,8,9 for k=0..4. - Hieronymus Fischer, May 30 2012
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LINKS
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Hieronymus Fischer, Table of n, a(n) for n = 1..10000
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FORMULA
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Contribution from Hieronymus Fischer, May 30 2012 (Start):
a(n) = ((2*b_m(n)) mod 8 + 4 + floor(b_m(n)/4) - floor((b_m(n)+1)/4))*10^m + sum_{j=0..m-1} ((2*b_j(n))) mod 10 + 2*floor((b_j(n)+4)/5) - floor((b_j(n)+1)/5) -floor(b_j(n)/5)))*10^j, where n>1, b_j(n)) = floor((n-1-5^m)/5^j), m = floor(log_5(n-1)).
a(1*5^n+1) = 4*10^n.
a(2*5^n+1) = 6*10^n.
a(3*5^n+1) = 8*10^n.
a(4*5^n+1) = 9*10^n.
a(n) = 4*10^log_5(n-1) for n=5^k+1,
a(n) < 4*10^log_5(n-1), else.
a(n) > 10^log_5(n-1) n>1.
a(n) = 4*A007091(n-1), iff the digits of A007091(n-1) are 0 or 1.
G.f.: g(x) = (x/(1-x))*sum_{j>=0} 10^j*x^5^j*(1-x^5^j)*(4 + 6x^5^j + 8(x^2)^5^j + 9(x^3)^5^j)/(1-x^5^(j+1)).
Also: g(x) = (x/(1-x))*(4*h_(5,1)(x) + 2*h_(5,2)(x) + 2*h_(5,3)(x) + h_(5,4)(x) - 9*h_(5,5)(x)), where h_(5,k)(x) = sum_{j>=0} 10^j*(x^5^j)^k/(1-(x^5^j)^5). (End)
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EXAMPLE
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a(1000) = 46999.
a(10^4) = 809999.
a(10^5) = 44499999.
a(10^6) = 668999999.
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CROSSREFS
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Cf. A061371, A029581.
Cf. A007091, A046034, A084544, A084984, A017042, A001743, A014261, A014263, A202267, A202268.
Sequence in context: A156673 A073866 A202260 * A113624 A113591 A029581
Adjacent sequences: A001741 A001742 A001743 * A001745 A001746 A001747
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KEYWORD
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base,nonn
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AUTHOR
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N. J. A. Sloane.
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EXTENSIONS
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Ambiguous comment deleted by Zak Seidov, May 25 2010
Examples added by Hieronymus Fischer, May 30 2012
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STATUS
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approved
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