OFFSET
0,2
COMMENTS
The sum of the digits of a(n) is divisible by 27. For example, 9^5 = 59049 and 5 + 9 + 0 + 4 + 9 = 27 * 1.
Number of 9 in a(n) is 3*n-1 for n > 0. - Seiichi Manyama, Sep 18 2018
FORMULA
a(n) = A002283(n)^5.
From Ilya Gutkovskiy, Apr 19 2016: (Start)
O.g.f.: 59049*x*(1 + 49940*x + 78366000*x^2 + 4994000000*x^3 + 10000000000*x^4)/((1 - x)*(1 - 10*x)*(1 - 100*x)*(1 - 1000*x)*(1 - 10000*x)*(1 - 100000*x)).
E.g.f.: -exp(x) + 5*exp(10*x) - 10*exp(100*x) + 10*exp(1000*x) - 5*exp(10000*x) + exp(100000*x). (End)
EXAMPLE
From Seiichi Manyama, Sep 18 2018: (Start)
n| a(n) can be divided into 5 parts for n > 1.
-+--------------------------------------------
1| 5 9 04 9
2| 9 50 99 004 99
3| 99 500 999 0004 999
4| 999 5000 9999 00004 9999
(End)
MAPLE
MATHEMATICA
(10^Range[0, 10] - 1)^5 (* Wesley Ivan Hurt, Apr 19 2016 *)
PROG
(Ruby)
(0..n).each{|i| p ('9' * i).to_i ** 5}
(PARI) a(n) = (10^n-1)^5; \\ Michel Marcus, Apr 19 2016
(Magma) [(10^n-1)^5 : n in [0..10]]; // Wesley Ivan Hurt, Apr 19 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Seiichi Manyama, Apr 19 2016
STATUS
approved