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A064753
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a(n) = n*7^n - 1.
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4
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6, 97, 1028, 9603, 84034, 705893, 5764800, 46118407, 363182462, 2824752489, 21750594172, 166095446411, 1259557135290, 9495123019885, 71213422649144, 531726889113615, 3954718737782518, 29311444762388081, 216579008522089716, 1595845325952240019
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OFFSET
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1,1
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LINKS
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FORMULA
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G.f.: (56*x^2-21*x+1)/((x-1)*(7*x-1)^2).
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MAPLE
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k:= 7; f:= gfun:-rectoproc({1 + (k-1)*n + k*n*a(n-1) - (n-1)*a(n) = 0, a(1) = k-1}, a(n), remember): map(f, [$1..20]); # Georg Fischer, Feb 19 2021
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MATHEMATICA
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Table[n 7^n-1, {n, 20}] (* or *) LinearRecurrence[{15, -63, 49}, {6, 97, 1028}, 20] (* Harvey P. Dale, Feb 12 2022 *)
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PROG
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CROSSREFS
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For a(n)=n*k^n-1 cf. -A000012 (k=0), A001477 (k=1), A003261 (k=2), A060352 (k=3), A060416 (k=4), A064751 (k=5), A064752 (k=6), this sequence (k=7), A064754 (k=8), A064755 (k=9), A064756 (k=10), A064757 (k=11), A064758 (k=12).
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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