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 A061418 a(n) = floor(a(n-1)*3/2) with a(1) = 2. 21
 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

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Last modified August 24 18:12 EDT 2019. Contains 326295 sequences. (Running on oeis4.)