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A171163 Number of children at height n in a doubly logarithmic tree. Leaves are at height 0. 1
0, 2, 2, 4, 16, 256, 65536, 4294967296, 18446744073709551616, 340282366920938463463374607431768211456, 115792089237316195423570985008687907853269984665640564039457584007913129639936 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
LINKS
Omer Berkman, Baruch Schieber and Uzi Vishkin, Optimal doubly logarithmic parallel algorithms based on finding all nearest smaller values, Journal of Algorithms, 14(1993)(3): 344-370.
FORMULA
a(0)=0, a(1)=2; for n>1, a(n) = 2^(2^(n-2)).
MATHEMATICA
Join[{0, 2}, Table[2^2^(n-2), {n, 2, 9}]] (* Harvey P. Dale, Feb 01 2014 *)
PROG
(Python)
def doubly_log_tree_children(n):
if n==0:
return 0
if n==1:
return 2
return 2**(2**(n-2))
CROSSREFS
Equals A001146 with the prefix 0, 2.
Cf. A165420. [R. J. Mathar, Dec 11 2009]
Sequence in context: A168088 A168089 A165420 * A129614 A070283 A070282
KEYWORD
nonn
AUTHOR
Chad Brewbaker, Dec 04 2009
EXTENSIONS
More terms from Harvey P. Dale, Feb 01 2014
STATUS
approved

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Last modified June 19 22:07 EDT 2024. Contains 373507 sequences. (Running on oeis4.)