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

 

Logo

Annual Appeal: Please make a donation (tax deductible in USA) to keep the OEIS running. Over 5000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A061418 a(n) = floor(a(n-1)*3/2) with a(1) = 2. 20
2, 3, 4, 6, 9, 13, 19, 28, 42, 63, 94, 141, 211, 316, 474, 711, 1066, 1599, 2398, 3597, 5395, 8092, 12138, 18207, 27310, 40965, 61447, 92170, 138255, 207382, 311073, 466609, 699913, 1049869, 1574803, 2362204, 3543306, 5314959, 7972438 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Can be stated as the number of animals starting from a single pair if any pair of animals can produce a single offspring (as in the game Minecraft, if the player allows offspring to fully grow before breeding again). - Denis Moskowitz, Dec 05 2012

LINKS

Harry J. Smith, Table of n, a(n) for n = 1..500

M. van de Vel, Determination of msd(L^n), J. Algebraic Combin., 9 (1999), 161-171. See Table 5. - N. J. A. Sloane, Mar 26 2012

FORMULA

a(n) = A061419(n)+1 = ceiling(K*(3/2)^n) where K=1.08151366859...

The constant K is 2/3*K(3) (see A083286). - Ralf Stephan, May 29, 2003

EXAMPLE

a(6) = floor(9*3/2) = 13.

MATHEMATICA

lst = {}; s = 2; Do[s = Floor[s*1.5]; AppendTo[lst, s], {n, 1, 5!}]; lst (* Vladimir Joseph Stephan Orlovsky, Nov 13 2008 *)

PROG

(MAGMA) [ n eq 1 select 2 else Floor(Self(n-1)*(3/2)): n in [1..39] ]; // Klaus Brockhaus, Nov 14 2008

(PARI) { a=4/3; for (n=1, 500, a=a*3\2; write("b061418.txt", n, " ", a) ) } \\ Harry J. Smith, Jul 22 2009

CROSSREFS

Cf. A002379, A034082, A061419, A003312.

First differences are in A073941.

Sequence in context: A101913 A121653 A238434 * A136423 A215245 A078932

Adjacent sequences:  A061415 A061416 A061417 * A061419 A061420 A061421

KEYWORD

nonn

AUTHOR

Henry Bottomley, May 02 2001

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 December 4 15:24 EST 2016. Contains 278750 sequences.