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A022335 Index of 2^n within sequence of numbers of form 2^i * 5^j. 1
1, 2, 3, 5, 7, 10, 13, 17, 21, 25, 30, 35, 41, 47, 54, 61, 68, 76, 84, 93, 102, 112, 122, 132, 143, 154, 166, 178, 191, 204, 217, 231, 245, 260, 275, 291, 307, 323, 340, 357, 375, 393, 412, 431, 450, 470, 490, 511, 532, 554, 576, 598, 621, 644, 668, 692, 717, 742, 767, 793 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Greedy inverse of A022332: a(n) = min {k : A022332(k) = n}. - R. J. Mathar, Aug 04 2016

LINKS

Table of n, a(n) for n=0..59.

FORMULA

a(n) = sum(i=0..n, 1 + floor(log(2^i)/log(5)) ). - Michel Marcus, Oct 02 2013

PROG

(PARI) a(n) = sum(i=0, n, 1 + floor(log(2^i)/log(5))); \\ Michel Marcus, Oct 02 2013

CROSSREFS

Cf. A003592, A022334.

Sequence in context: A265250 A090499 A229170 * A022780 A075353 A132278

Adjacent sequences:  A022332 A022333 A022334 * A022336 A022337 A022338

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified May 31 19:40 EDT 2020. Contains 334748 sequences. (Running on oeis4.)