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A090616 Highest power of 4 dividing n!. 10
0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 5, 5, 7, 7, 8, 8, 9, 9, 9, 9, 11, 11, 11, 11, 12, 12, 13, 13, 15, 15, 16, 16, 17, 17, 17, 17, 19, 19, 19, 19, 20, 20, 21, 21, 23, 23, 23, 23, 24, 24, 25, 25, 26, 26, 27, 27, 28, 28, 28, 28, 31, 31, 32, 32, 33, 33, 33, 33, 35, 35, 35, 35, 36 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,7

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..10000

FORMULA

a(n) =A090622(n, 4) =[A011371(n)/2] =[([n/2]+[n/4]+[n/8]+[n/16]+...)/2].

EXAMPLE

a(6)=2 since 6!=720 =4^2*45.

MATHEMATICA

IntegerExponent[Range[0, 100]!, 4] (* Vincenzo Librandi, Mar 10 2013 *)

PROG

(PARI) a(n) = valuation( n!, 4 ); /* Joerg Arndt, Mar 10 2013 */

CROSSREFS

Cf. A011371, A054861, A027868, A054896.

Sequence in context: A069924 A225559 A082479 * A186704 A067434 A336348

Adjacent sequences:  A090613 A090614 A090615 * A090617 A090618 A090619

KEYWORD

nonn

AUTHOR

Henry Bottomley, Dec 06 2003

STATUS

approved

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Last modified September 18 23:30 EDT 2020. Contains 337175 sequences. (Running on oeis4.)