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A036293
a(n) = n*7^n.
5
0, 7, 98, 1029, 9604, 84035, 705894, 5764801, 46118408, 363182463, 2824752490, 21750594173, 166095446412, 1259557135291, 9495123019886, 71213422649145, 531726889113616, 3954718737782519, 29311444762388082, 216579008522089717, 1595845325952240020, 11729463145748964147
OFFSET
0,2
FORMULA
From Harvey P. Dale, Aug 08 2011: (Start)
a(n) = 14*a(n-1) - 49*a(n-2) with a(0)=0 and a(1)=7.
G.f.: (7*x)/(7*x-1)^2. (End)
From Amiram Eldar, Jul 20 2020: (Start)
Sum_{n>=1} 1/a(n) = log(7/6).
Sum_{n>=1} (-1)^(n+1)/a(n) = log(8/7). (End)
From Elmo R. Oliveira, Sep 09 2024: (Start)
E.g.f.: 7*x*exp(7*x).
a(n) = n*A000420(n). (End)
MATHEMATICA
Table[n 7^n, {n, 0, 30}] (* or *) LinearRecurrence[{14, -49}, {0, 7}, 31] (* Harvey P. Dale, Aug 08 2011 *)
PROG
(Magma) [n*7^n: n in [0..20]] ; // Vincenzo Librandi, Aug 09 2011
CROSSREFS
Cf. A000420.
Sequence in context: A267669 A288681 A124092 * A133679 A219406 A267664
KEYWORD
nonn,easy
STATUS
approved