OFFSET
1,1
COMMENTS
(a(1), ..., a(n-1), a(n)-1) is an integer solution to the equation Sum_{k=1}^n k/x(k) = 1.
LINKS
Robert Israel, Table of n, a(n) for n = 1..12
R. Israel, Set of solutions to a sum, Mathematics StackExchange.
N. J. A. Sloane, A Nasty Surprise in a Sequence and Other OEIS Stories, Experimental Mathematics Seminar, Rutgers University, Oct 10 2024, Youtube video; Slides [Mentions this sequence]
FORMULA
EXAMPLE
1/1 = 1.
1/2 + 2/4 = 1.
1/2 + 2/5 + 3/30 = 1.
1/2 + 2/5 + 3/31 + 4/1240 = 1.
1/2 + 2/5 + 3/31 + 4/1241 + 5/1923550 = 1.
MAPLE
a[1]:= 2:
for n from 1 to 10 do a[n+1]:= 1 + (a[n]^2 - a[n])*(1+1/n) od:
seq(a[i], i=1..11);
MATHEMATICA
Fold[Append[#1, 1 + (Last[#1]^2 - Last[#1]) (1 + 1/#2)] &, {2}, Range@ 8] (* Michael De Vlieger, Nov 21 2017 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert Israel, Nov 21 2017
STATUS
approved