Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #13 Sep 08 2022 08:46:14
%S 1,3,3,7625597484987
%N a(1) = 1, a(2) = 3, a(n)= H_4(a(n-1),a(n-2)).
%C See A054871 for definitions and key links.
%C Possible other sequence with the same 4 entries:
%C a(1)=1;
%C a(2)= 3;
%C a(n)=a(n-1)^a(n-2)^a(n-2);
%t RecurrenceTable[{a[1]==1, a[2]==3, a[n]==a[n-1]^a[n-2]^a[n-2]}, a, {n, 4}] (* _Vincenzo Librandi_, Dec 17 2015 *)
%o (Magma) I:=[1,3]; [n le 2 select I[n] else Self(n-1)^Self(n-2)^Self(n-2): n in [1..5]]; // _Vincenzo Librandi_, Dec 17 2015
%K nonn
%O 1,2
%A _Natan Arie Consigli_, Dec 16 2015