A087774 - OEIS

%I #5 Mar 30 2012 17:34:13

%S 11,2,2,1,2,5,1,2,8,1,2,11,1,2,14,1,2,17,1,2,20,1,2,23,1,2,26,1,2,29,

%T 1,2,32,1,2,35,1,2,38,1,2,41,1,2,44,1,2,47,1,2,50,1,2,53,1,2,56,1,2,

%U 59,1,2,62,1,2,65,1,2,68,1,2,71,1,2,74,1,2,77,1,2,80,1,2,83,1,2,86,1,2,89,1

%N a[1] = 1, a[2] = a[3] = 2; a[n] = 3*a[a[n-1]] - 3*a[n-a[n-1]]+a[n-3].

%C A recursive finite third derivative sequence. A tick-tock sequence of the form 1,2,a(n-3)+3

%t hg[n_Integer?Positive] := hg[n] =3*hg[hg[n-1]] -3*hg[n-hg[n-1]]+hg[n-3] hg[1]=1 hg[2]=2 hg[3]=2 digits=200 a=Table[hg[n], {n, 1, digits}]

%Y Cf. A004001, A087775.

%K nonn

%O 0,1

%A _Roger L. Bagula_, Oct 04 2003