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A063511 a(n) = a(floor(square root(n)) * 2. 0
1, 2, 2, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..105.

Martin F├╝rer, Faster integer multiplication, Proceedings of the 39th Annual ACM Symposium on Theory of Computing, June 11-13 2007.

Index to divisibility sequences

FORMULA

a(n) = 2^lg*(n), where lg*(x) = 0 if x <= 1 and 1 + lg*(log_2(x)) otherwise. - Charles R Greathouse IV, Apr 09 2012

PROG

(PARI) a(n)=my(t); while(n>1, n=log(n+.5)\log(2); t++); 2^t \\ Charles R Greathouse IV, Apr 09 2012

CROSSREFS

Sequence in context: A179932 A267649 A071805 * A283207 A164717 A164715

Adjacent sequences:  A063508 A063509 A063510 * A063512 A063513 A063514

KEYWORD

easy,nonn

AUTHOR

Reinhard Zumkeller, Jul 30 2001

STATUS

approved

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Last modified April 1 10:33 EDT 2020. Contains 333159 sequences. (Running on oeis4.)