A245384 - OEIS

%I #20 Sep 08 2022 08:46:08

%S 1,2,3,8,54,1320,570672,40677571440,30641887385179424640,

%T 711307017047678652146384291462042880,

%U 886599784992546696966754646294076268713472764725575212247451289600

%N a(n) = (1 + a(n-1)) * a(n-2) * a(n-3) with a(1) = 1, a(2) = 2, a(3) = 3.

%H Michael Somos, <a href="/A245384/b245384.txt">Table of n, a(n) for n = 1..11</a>

%F a(n) = A245366(n) - 1 for n>0.

%F a(n) = A245283(n+3) / A245283(n+2) for n>0.

%t a[ n_] := If[ n < 4, Max[1, n], a[n] = (1 + a[n-1]) a[n-2] a[n-3]];

%o (PARI) {a(n) = if( n<4, max(1, n), (1 + a(n-1)) * a(n-2) * a(n-3))};

%o (Magma) I:=[1,2,3]; [n le 3 select I[n] else (1 + Self(n-1))*Self(n-2)* Self(n-3): n in [1..15]]; // _G. C. Greubel_, Aug 05 2018

%Y Cf. A245283, A245366.

%K nonn

%O 1,2

%A _Michael Somos_, Aug 21 2014