|
|
A038444
|
|
Sums of 2 distinct powers of 10.
|
|
27
|
|
|
11, 101, 110, 1001, 1010, 1100, 10001, 10010, 10100, 11000, 100001, 100010, 100100, 101000, 110000, 1000001, 1000010, 1000100, 1001000, 1010000, 1100000, 10000001, 10000010, 10000100, 10001000, 10010000, 10100000, 11000000
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
FORMULA
|
G.f.: (10*x - 55*x^2 + Sum_{d>=1} (4*10^d+5)*x^((d^2-d)/2+1) - Sum_{d>=1} (445*10^(d-1)+5)*x^((d^2-d)/2+2))/(5*(1-x)*(1-10*x)). - Robert Israel, Oct 14 2016
|
|
MAPLE
|
seq(seq(10^d + 10^j, j=0..d-1), d=1..10); # Robert Israel, Oct 14 2016
|
|
MATHEMATICA
|
Sort[Total/@Subsets[10^Range[0, 7], {2}]] (* Harvey P. Dale, Apr 20 2012 *)
|
|
PROG
|
(Haskell)
a038444 n = a038444_list !! (n-1)
a038444_list = 11 : f [11] 90 where
f xs@(x:_) z = ys ++ f ys (10 * z) where
ys = (x + z) : map (* 10) xs
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|