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A124167 a(n) = 10*(10^n-1). 1
0, 90, 990, 9990, 99990, 999990, 9999990, 99999990, 999999990, 9999999990, 99999999990, 999999999990, 9999999999990, 99999999999990, 999999999999990, 9999999999999990, 99999999999999990, 999999999999999990 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

a(n - 1) is the maximum difference between an n-digit number (written in base 10, nonzero leading digit) and the product of its digits. For n>1, it is also a number meeting that bound. See A070565. - Devin Akman, Apr 17 2019

LINKS

Michael De Vlieger, Table of n, a(n) for n = 0..999

Index entries for linear recurrences with constant coefficients, signature (11,-10).

FORMULA

a(n) = 10*A002283(n).

From G. C. Greubel, Jun 30 2019: (Start)

a(n) = 90*A002275(n).

a(n) = 11*a(n-1) - 10*a(n-2).

G.f.: 10*(1/(1-10*x) - 1/(1-x)).

E.g.f.: 10*(exp(10*x) - exp(x)). (End)

MAPLE

a:=n->sum (10^(n-j+2)-10^(n-j+1), j=0..n): seq(a(n), n=0..20);

MATHEMATICA

Array[10 (10^# - 1) &, 20, 0] (* Michael De Vlieger, Apr 21 2019 *)

PROG

(PARI) vector(20, n, n--; 10*(10^n -1)) \\ G. C. Greubel, Jun 30 2019

(MAGMA) [10*(10^n -1): n in [0..20]]; // G. C. Greubel, Jun 30 2019

(Sage) [10*(10^n -1) for n in (0..20)] # G. C. Greubel, Jun 30 2019

(GAP) List([0..20], n-> 10*(10^n -1)) # G. C. Greubel, Jun 30 2019

CROSSREFS

Partial sums give 10*A099676.

Cf. A002283, A002275, A070565.

Sequence in context: A101243 A173483 A202960 * A223364 A048548 A013427

Adjacent sequences:  A124164 A124165 A124166 * A124168 A124169 A124170

KEYWORD

easy,nonn

AUTHOR

Zerinvary Lajos, Dec 02 2006

STATUS

approved

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Last modified September 21 15:09 EDT 2019. Contains 327270 sequences. (Running on oeis4.)