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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..1000

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

Cf. A000523, A115636.

Sequence in context: A202686 A134660 A132383 * A242954 A062732 A100777

Adjacent sequences:  A115636 A115637 A115638 * A115640 A115641 A115642

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Jan 27 2006

STATUS

approved

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Last modified September 27 19:37 EDT 2022. Contains 357063 sequences. (Running on oeis4.)