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
(SageMath) [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
KEYWORD
easy,nonn
AUTHOR
Zerinvary Lajos, Dec 02 2006
STATUS
approved