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A124908 a(n) = least integer j >= 0 such that n = floor((2^j)/(5^k)) for some integer k >= 0. 3
0, 1, 4, 2, 7, 5, 33, 3, 38, 8, 36, 6, 13, 34, 55, 4, 25, 39, 60, 9, 23, 37, 44, 58, 7, 14, 28, 35, 49, 56, 70, 5, 19, 26, 33, 40, 54, 61, 68, 10, 17, 24, 31, 103, 38, 45, 52, 59, 66, 73, 8, 15, 22, 29, 101, 36, 43, 115, 50, 57, 64, 136, 71, 6, 13, 85, 20, 27, 99, 34, 106, 41, 48 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

The k-sequence is A124916.

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

FORMULA

a(2^j) = j. - Robert Israel, Jul 05 2018

EXAMPLE

1 = floor(2^0/5^0), 2 = floor(2^1/5^0), 3 = floor(2^4/5^1), 4 = floor(2^2/5^0), ...,

so j-sequence = (0,1,4,2,...); k-sequence = (0,0,1,0,...).

MAPLE

f:= proc(n) local k;

if n = 2^ilog2(n) then return ilog2(n) fi;

for k from 1 do if ilog2(n*5^k) <> ilog2((n+1)*5^k) then return ilog2((n+1)*5^k) fi od

end proc:

map(f, [$1..100]); # Robert Israel, Jul 05 2018

CROSSREFS

Cf. A124916.

Sequence in context: A271479 A259927 A002560 * A260593 A143370 A307869

Adjacent sequences:  A124905 A124906 A124907 * A124909 A124910 A124911

KEYWORD

nonn,look

AUTHOR

Clark Kimberling, Nov 12 2006

STATUS

approved

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Last modified May 31 13:01 EDT 2020. Contains 334748 sequences. (Running on oeis4.)