A151752 -id:A151752 - cp's OEIS frontend

A151753 Leading digits of A151752.

5, 7, 3, 9, 5, 3, 3, 9, 1, 3, 7, 7, 3, 7, 7, 5, 1, 5, 7, 9, 3, 7, 3, 3, 9, 9, 9, 5, 3, 7, 1, 7, 9, 5, 7, 9, 3, 1, 3, 9, 5, 7, 5, 5, 7, 7, 1, 1, 3, 1, 9, 5, 9, 1, 9, 5, 5, 7, 7, 7, 7, 7, 9, 7, 9, 9, 7, 7, 3, 3, 5, 9, 7, 7, 1, 1, 5, 9, 7, 1, 5, 1, 7, 5, 9, 1, 7, 9, 3, 5, 3, 9, 1, 7, 9, 9, 1, 9, 9, 1, 5, 3, 7, 5, 9

Offset: 1

Max Alekseyev, Jun 17 2009

Alois P. Heinz, Table of n, a(n) for n = 1..10000

Cf. A000030, A151752.

a:= proc(n) option remember; local k, l; if n=1 then b(1):= 5; 5 else a(n-1); l:= b(n-1); for k from 1 to 9 by 2 while (parse(cat(k, l)) mod 5^n)<>0 do od; b(n):= parse(cat(k, l)); k fi end:
seq(a(n), n=1..120); # Alois P. Heinz, Jun 18 2009

a(n) = A000030(A151752(n)). - Omar E. Pol, Jul 04 2019

More terms from Alois P. Heinz, Jun 18 2009

A151754 Number of n-digit numbers that are divisible by 5^n.

Original entry on oeis.org

1, 3, 7, 14, 28, 57, 115, 230, 460, 921, 1843, 3686, 7372, 14745, 29491, 58982, 117964, 235929, 471859, 943718, 1887436, 3774873, 7549747, 15099494, 30198988, 60397977, 120795955, 241591910, 483183820, 966367641, 1932735283, 3865470566, 7730941132, 15461882265

Offset: 1

Robert G. Wilson v, Jun 17 2009

			a(1)=1 because 5 divides only 5,
a(2)=3 because 25 divides {25, 50 & 75},
a(3)=7 because 125 divides {125, 250, 375, 500, 625, 750 & 925}, etc.

Index entries for linear recurrences with constant coefficients, signature (3,-3,3,-2).

Cf. A151752.

f[n_] := Floor[(10^n - 1)/5^n] - Floor[10^(n - 1)/5^n]; Array[f, 35]
LinearRecurrence[{3,-3,3,-2},{1,3,7,14},30] (* Harvey P. Dale, Feb 20 2016 *)

Limit_{n -> oo} a(n+1)/a(n) = 2.
a(n) = [(9/10)*2^n]. - David W. Wilson, Jun 18 2009
G.f.: x * ( 1+x^2-x^3 ) / ( (x-1)*(2*x-1)*(x^2+1) ). - R. J. Mathar, Feb 20 2011

cp's OEIS Frontend

A151753 Leading digits of A151752.

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