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A064753
a(n) = n*7^n - 1.
5
6, 97, 1028, 9603, 84034, 705893, 5764800, 46118407, 363182462, 2824752489, 21750594172, 166095446411, 1259557135290, 9495123019885, 71213422649144, 531726889113615, 3954718737782518, 29311444762388081, 216579008522089716, 1595845325952240019
OFFSET
1,1
FORMULA
From Alois P. Heinz, Feb 19 2021: (Start)
G.f.: (56*x^2-21*x+1)/((x-1)*(7*x-1)^2).
a(n) = A036293(n) - 1. (End)
MAPLE
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
MATHEMATICA
Table[n 7^n-1, {n, 20}] (* or *) LinearRecurrence[{15, -63, 49}, {6, 97, 1028}, 20] (* Harvey P. Dale, Feb 12 2022 *)
PROG
(Magma) [ n*7^n-1: n in [1..20]]; // Vincenzo Librandi, Sep 16 2011
CROSSREFS
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).
Cf. A036293.
Sequence in context: A213797 A285025 A288544 * A322739 A244251 A187522
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Oct 19 2001
STATUS
approved