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A022334 Index of 5^n within sequence of numbers of form 2^i * 5^j. 1
1, 4, 9, 16, 26, 38, 52, 69, 88, 109, 133, 159, 187, 218, 251, 286, 324, 364, 406, 451, 498, 547, 599, 653, 709, 768, 829, 892, 958, 1026, 1096, 1168, 1243, 1320, 1399, 1481, 1565, 1651, 1740, 1831, 1924, 2020, 2118, 2218, 2321, 2426, 2533, 2643, 2755, 2869, 2986 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Greedy inverse of A022333: a(n) = min{k: A022333(k) = n}. - R. J. Mathar, Aug 04 2016

LINKS

Table of n, a(n) for n=0..50.

FORMULA

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

PROG

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

CROSSREFS

Cf. A003592, A022335.

Sequence in context: A050461 A189835 A183764 * A073171 A328363 A049739

Adjacent sequences:  A022331 A022332 A022333 * A022335 A022336 A022337

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified September 17 22:14 EDT 2021. Contains 347489 sequences. (Running on oeis4.)