%I #8 Sep 08 2022 08:44:40
%S 1,6,37,1369,297073,385303681,2996506727137,139808014368031009,
%T 39137436118143496566433,65735903040447825272422496161,
%U 662466512863011927404416372294221217,40056817423347655955546590948840276184277409
%N a(0)=1, a(1)=6, a(n) = sum_{k=0}^{k=n-1} 6^k a(k).
%F a(n) = (6^(n-2) + 1) * a(n-1). - _Vincenzo Librandi_, Nov 11 2012
%o (Magma) I:=[1, 6, 37]; [n le 3 select I[n] else (6^(n-2)+1)*Self(n-1): n in [1..15]]; // _Vincenzo Librandi_, Nov 11 2012
%K nonn,easy
%O 0,2
%A _Olivier GĂ©rard_