login
A115639
First column of divide-and-conquer triangle A115636.
3
1, 1, 4, 4, 4, 4, 16, 16, 16, 16, 16, 16, 16, 16, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256
OFFSET
0,3
LINKS
FORMULA
G.f.: (1/(1-x))*( 1/4 + (3/4)*Sum_{k>=1} 4^(k-1)*x^(2^k-2) ).
a(n) = 4^(floor(log_2(n+2)) - 1). - G. C. Greubel, Nov 23 2021
MATHEMATICA
4^(Floor[Log[2, Range[0, 80] +2]] -1) (* G. C. Greubel, Nov 23 2021 *)
PROG
(Magma) [4^(Ilog2(n+2) -1) : n in [0..80] ]; // G. C. Greubel, Nov 23 2021
(Sage) [4^(floor(log(n+2, 2)) -1) for n in (0..80)] # G. C. Greubel, Nov 23 2021
CROSSREFS
Sequence in context: A202686 A134660 A132383 * A242954 A062732 A100777
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Jan 27 2006
STATUS
approved