The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A025632

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A025632

Numbers of form 7^i*10^j, with i, j >= 0.
(history; published version)

#17 by Vaclav Kotesovec at Fri Sep 25 05:10:39 EDT 2020

STATUS

editing

approved

#16 by Vaclav Kotesovec at Fri Sep 25 05:10:34 EDT 2020

FORMULA

a(n) ~ exp(sqrt(2*log(7)*log(10)*n)) / sqrt(70). - Vaclav Kotesovec, Sep 25 2020

STATUS

approved

editing

#15 by Joerg Arndt at Fri Sep 25 04:34:38 EDT 2020

STATUS

reviewed

approved

#14 by Michel Marcus at Fri Sep 25 04:29:00 EDT 2020

STATUS

proposed

reviewed

#13 by Amiram Eldar at Fri Sep 25 04:20:22 EDT 2020

STATUS

editing

proposed

#12 by Amiram Eldar at Fri Sep 25 04:17:20 EDT 2020

MATHEMATICA

n = 10^6; Flatten[Table[7^i*10^j, {i, 0, Log[7, n]}, {j, 0, LogLog10[10, n/7^i]}]] // Sort (* Amiram Eldar, Sep 25 2020 *)

#11 by Amiram Eldar at Fri Sep 25 03:49:24 EDT 2020

FORMULA

Sum_{n>=1} 1/a(n) = (7*10)/((7-1)*(10-1)) = 35/27. - Amiram Eldar, Sep 25 2020

MATHEMATICA

n = 10^6; Flatten[Table[7^i*10^j, {i, 0, Log[7, n]}, {j, 0, Log[10, n/7^i]}]] // Sort (* Amiram Eldar, Sep 25 2020 *)

STATUS

approved

editing

#10 by Charles R Greathouse IV at Wed Jan 10 12:31:35 EST 2018

STATUS

editing

approved

#9 by Charles R Greathouse IV at Wed Jan 10 12:31:23 EST 2018

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*=7)); Set(v) \\ Charles R Greathouse IV, Jan 10 2018

STATUS

approved

editing

#8 by Reinhard Zumkeller at Fri May 15 16:53:09 EDT 2015

STATUS

editing

approved