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A015507 a(1)=1, a(n) = sum_{k=1}^{k=n-1} (6^k-1)/5 a(k). 0

%I

%S 1,1,8,352,91520,142405120,1328924579840,74403829376081920,

%T 24994031979330942894080,50376471215620688640734003200,

%U 609214555257707874214915513922355200,44204249911340791820804231319883906967142400

%N a(1)=1, a(n) = sum_{k=1}^{k=n-1} (6^k-1)/5 a(k).

%F a(n) = ((6^(n-1) + 4)/5) * a(n-1). - _Vincenzo Librandi_, Nov 12 2012

%o (MAGMA) I:=[1, 1, 8]; [n le 3 select I[n] else ((6^(n-1) + 4)/5) * Self(n-1): n in [1..15]]; // _Vincenzo Librandi_, Nov 12 2012

%K nonn,easy

%O 1,3

%A _Olivier GĂ©rard_

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Last modified July 4 12:28 EDT 2022. Contains 355075 sequences. (Running on oeis4.)