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A025612 Numbers of form 2^i*10^j, with i, j >= 0. 15
1, 2, 4, 8, 10, 16, 20, 32, 40, 64, 80, 100, 128, 160, 200, 256, 320, 400, 512, 640, 800, 1000, 1024, 1280, 1600, 2000, 2048, 2560, 3200, 4000, 4096, 5120, 6400, 8000, 8192, 10000, 10240, 12800, 16000, 16384, 20000, 20480, 25600, 32000, 32768, 40000, 40960 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

FORMULA

Sum_{n>=1} 1/a(n) = (2*10)/((2-1)*(10-1)) = 20/9. - Amiram Eldar, Sep 25 2020

a(n) ~ exp(sqrt(2*log(2)*log(10)*n)) / sqrt(20). - Vaclav Kotesovec, Sep 25 2020

MATHEMATICA

n = 10^5; Flatten[Table[2^i*10^j, {i, 0, Log2[n]}, {j, 0, Log10[n/2^i]}]] // Sort (* Amiram Eldar, Sep 25 2020 *)

PROG

(PARI) list(lim)=my(v=List(), N); for(n=0, logint(lim\=1, 10), N=10^n; while(N<=lim, listput(v, N); N<<=1)); Set(v) \\ Charles R Greathouse IV, Jan 10 2018

CROSSREFS

Subsequence of A000079 and A011557.

Subsequences: A025621 and A025634.

Sequence in context: A287178 A093547 A068382 * A335239 A102248 A161374

Adjacent sequences:  A025609 A025610 A025611 * A025613 A025614 A025615

KEYWORD

easy,nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified October 29 19:29 EDT 2020. Contains 338069 sequences. (Running on oeis4.)