This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A170838 G.f.: Prod_{k >= 0} (1 + x^(2^k-1) + 3x^(2^k)). 2

%I

%S 2,5,9,11,11,24,36,29,11,24,38,44,57,108,135,83,11,24,38,44,57,108,

%T 137,98,57,110,158,189,279,459,486,245,11,24,38,44,57,108,137,98,57,

%U 110,158,189,279,459,488,260,57,110,158,189,279,461,509,351,281,488,663,846,1296

%N G.f.: Prod_{k >= 0} (1 + x^(2^k-1) + 3x^(2^k)).

%H David Applegate, Omar E. Pol and N. J. A. Sloane, <a href="http://neilsloane.com/doc/tooth.pdf">The Toothpick Sequence and Other Sequences from Cellular Automata</a>, Congressus Numerantium, Vol. 206 (2010), 157-191. [There is a typo in Theorem 6: (13) should read u(n) = 4.3^(wt(n-1)-1) for n >= 2.]

%H N. J. A. Sloane, <a href="/wiki/Catalog_of_Toothpick_and_CA_Sequences_in_OEIS">Catalog of Toothpick and Cellular Automata Sequences in the OEIS</a>

%p Maple program for A170838-A170852, A162956, A170854-A170872.

%p G := proc(a,b,c); mul( 1 + a*x^(2^n-1) + b*x^(2^n), n=c..20); end;

%p f := proc(a,b,c) seriestolist(series(G(a,b,c),x,120)); end;

%p at:=170838:

%p for a from 1 to 2 do for c from 0 to 2 do

%p b:=3;

%p t1:=f(a,b,c);

%p lprint( format(t1,at) );

%p lprint("G.f.: Prod_{k >= ", c, "} (1 +",a,"* x^(2^k-1) +",b,"* x^(2^k)).");

%p at:=at+1; od: od:

%p for b from 1 to 3 do for c from 0 to 2 do

%p a:=3;

%p t1:=f(a,b,c);

%p lprint( format(t1,at) );

%p lprint("G.f.: Prod_{k >= ", c, "} (1 +",a,"* x^(2^k-1) +",b,"* x^(2^k)).");

%p at:=at+1; od: od:

%p h:=proc(r,s,a,b) local s1,n,i,j;

%p s1:=array(0..120);

%p s1[0]:=r; s1[1]:=s;

%p for n from 2 to 120 do i:=floor(log(n)/log(2));

%p j:=n-2^i; s1[n]:=a*s1[j]+b*s1[j+1]; od:

%p [seq(s1[n],n=0..120)];

%p end;

%p l1:=[[0,1],[1,0],[1,1],[1,2]];

%p l2:=[[3,1],[3,2],[1,3],[2,3],[3,3]];

%p for i from 1 to 4 do for j from 1 to 5 do

%p r:=l1[i][1];

%p s:=l1[i][2];

%p a:=l2[j][1];

%p b:=l2[j][2];

%p t1:=h(r,s,a,b);

%p lprint(format(t1,at)); at:=at+1;

%p lprint("a(0)=",r,", a(1)=", s, "; a(2^i+j)=",a,"*a(j)+",b,"a(j+1) for 0 <= j < 2^i.");

%p od: od:

%Y A170838-A170852, A170854-A170872 were added to supplement _Gary W. Adamson_'s A162956.

%K nonn

%O 0,1

%A _N. J. A. Sloane_, Jan 02 2010

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 23 19:07 EDT 2019. Contains 323528 sequences. (Running on oeis4.)