login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A152968 a(n) = A139251(n+1)/2. 17
1, 2, 2, 2, 4, 6, 4, 2, 4, 6, 6, 8, 14, 16, 8, 2, 4, 6, 6, 8, 14, 16, 10, 8, 14, 18, 20, 30, 44, 40, 16, 2, 4, 6, 6, 8, 14, 16, 10, 8, 14, 18, 20, 30, 44, 40, 18, 8, 14, 18, 20, 30, 44, 42, 28, 30, 46, 56, 70, 104, 128, 96, 32, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Also, first differences of toothpicks numbers A152998. [From Omar E. Pol, Jan 02 2009]

LINKS

Table of n, a(n) for n=1..64.

David Applegate, Omar E. Pol and N. J. A. Sloane, The Toothpick Sequence and Other Sequences from Cellular Automata

N. J. A. Sloane, Catalog of Toothpick and Cellular Automata Sequences in the OEIS

FORMULA

Write n = 2^i +j, 0 <= j < 2^i; then a(n) = Sum_k 2^(wt(j+k)-k)*binomial(wt(j+k),k). except that a(2^r-1) = 2^(r-1). - N. J. A. Sloane, Jun 03 2009, Jul 16 2009

G.f.: x*(Prod(1+x^(2^k-1)+2*x^(2^k),k=0..oo)-1)/(1+2*x). - N. J. A. Sloane, Jun 05 2009

EXAMPLE

Triangle begins:

.1;

.2,2;

.2,4,6,4;

.2,4,6,6,8,14,16,8;

.2,4,6,6,8,14,16,10,8,14,18,20,30,44,40,16;

....

Rows approach A151688. - N. J. A. Sloane, Jun 03 2009

CROSSREFS

Cf. A139250, A139251, A139252, A152978, A152980, A153006, A152998.

Sequence in context: A278502 A278501 A278231 * A222177 A240433 A217637

Adjacent sequences:  A152965 A152966 A152967 * A152969 A152970 A152971

KEYWORD

nonn

AUTHOR

Omar E. Pol, Dec 16 2008, Dec 20 2008

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified August 17 22:32 EDT 2018. Contains 313817 sequences. (Running on oeis4.)