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A024121
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a(n) = 10^n - n^7.
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2
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1, 9, -28, -1187, -6384, 21875, 720064, 9176457, 97902848, 995217031, 9990000000, 99980512829, 999964168192, 9999937251483, 99999894586496, 999999829140625, 9999999731564544, 99999999589661327, 999999999387779968
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,2
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 0..300
Index entries for linear recurrences with constant coefficients, signature (18,-108,336,-630,756,-588,288,-81,10).
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FORMULA
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From Stefano Spezia, Oct 04 2018: (Start)
a(n) = 18*a(n - 1) - 108*a(n - 2) + 336*a(n - 3) - 630*a(n - 4) + 756*a(n - 5) - 588*a(n - 6) + 288*a(n - 7) - 81*a(n - 8) + 10*a(n - 9) for n > 8.
G.f.: -((1 - 9*x - 82*x^2 - 47*x^3 + 9564*x^4 + 22913*x^5 + 11818*x^6 + 1191*x^7 + 11*x^8)/((-1 + x)^8*(-1 + 10*x))).
E.g.f.: exp(x)*(exp(9*x) - x - 63*x^2 - 301*x^3 - 350*x^4 - 140*x^5 - 21*x^6 - x^7).
(End)
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MAPLE
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seq(10^n-n^7, n=0..20); # Muniru A Asiru, Oct 16 2018
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MATHEMATICA
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a[n_]:=10^n - n^7; Array[a, 50, 0] (* Stefano Spezia, Oct 04 2018 *)
LinearRecurrence[{18, -108, 336, -630, 756, -588, 288, -81, 10}, {1, 9, -28, -1187, -6384, 21875, 720064, 9176457, 97902848}, 20] (* Harvey P. Dale, Sep 16 2021 *)
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PROG
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(Magma) [10^n-n^7: n in [0..20]]; // Vincenzo Librandi, Jul 01 2011
(PARI) a(n)=10^n-n^7 \\ Charles R Greathouse IV, Jul 01 2011
(GAP) List([0..20], n->10^n-n^7); # Muniru A Asiru, Oct 16 2018
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CROSSREFS
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Cf. A011557 (10^n), A001015 (n^7).
Sequence in context: A306843 A277511 A041154 * A205144 A258483 A044976
Adjacent sequences: A024118 A024119 A024120 * A024122 A024123 A024124
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KEYWORD
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sign,easy
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AUTHOR
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N. J. A. Sloane
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STATUS
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approved
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