

A061418


a(n) = floor(a(n1)*3/2) with a(1) = 2.


24



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
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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
Maximum number of partial products that can be added in a Wallace tree multiplier with n1 full adder stages.  Chinmaya Dash, Aug 19 2020


LINKS



FORMULA

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


EXAMPLE

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


PROG

(Magma) [ n eq 1 select 2 else Floor(Self(n1)*(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
(PARI) first(n) = my(v=vector(n)); v[1]=2; for(i=2, n, v[i]=v[i1]*3\2); v \\ Iain Fox, Jul 15 2022
(Python)
from itertools import islice
def A061418_gen(): # generator of terms
a = 2
while True:
yield a
a += a>>1


CROSSREFS



KEYWORD

nonn,easy


AUTHOR



STATUS

approved



