OFFSET
1,3
REFERENCES
M. Archibald, A. Blecher and A. Knopfmacher, Fixed points in compositions and words, accepted by the Journal of Integer Sequences.
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..500
M. Archibald, A. Blecher, and A. Knopfmacher, Fixed Points in Compositions and Words, J. Int. Seq., Vol. 23 (2020), Article 20.11.1.
FORMULA
G.f.: Sum_{j>=1} (x/(1-x))^(j-1) j x^j Sum_{k>=j} Product_{i=j+1..k} (x/(1-x) - x^i).
EXAMPLE
For n=3 the a(3)=3 values are the first 1 in the composition 111 and the 2 in the composition 12 (the compositions 21 and 3 do not have any fixed points).
CROSSREFS
KEYWORD
nonn
AUTHOR
Margaret Archibald, Jun 18 2020
EXTENSIONS
a(21)-a(34) from Alois P. Heinz, Jun 18 2020
STATUS
approved