OFFSET
1,1
COMMENTS
For d >=2, the m with d digits are the solutions of x^2 + x - 9*10^(d-1)*d - 10^(d-1) == 0 (mod 2*10^d) with 10^(d-1) <= x < 10^d. - Robert Israel, Aug 08 2016
LINKS
Robert Israel, Table of n, a(n) for n = 1..1792
EXAMPLE
0.1+0.2+0.3+0.4 = 1 hence 4 is in the sequence.
MAPLE
F:= proc(d) local x, S;
S:= map(t -> subs(t, x), [msolve(x^2 + x - 9*10^(d-1)*d - 10^(d-1), 2*10^d)]);
op(sort(select(t -> t >= 10^(d-1) and t < 10^d, S)))
end proc:
4, seq(F(d), d=2..30); # Robert Israel, Aug 08 2016
MATHEMATICA
Flatten[Position[IntegerQ /@ Table[ Sum[10^-Length[IntegerDigits[i]]*i, {i, j}], {j, 1, 50000}], True]] (from Vit Planocka)
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Benoit Cloitre, Aug 30 2003
EXTENSIONS
One more term from Vit Planocka (planocka(AT)mistral.cz), Sep 24 2003
Terms a(9) - a(15) from John W. Layman, Jun 03 2005
a(16) - a(18) from Ryan Propper, Aug 25 2005
STATUS
approved