13333333333
domain: N
Appears in sequences
- Number of Fibonacci numbers F(k), k <= 10^n, which end in 9.at n=10A073556
- Expansion of g.f. (1+2*x)/((1-x)*(1-10*x)).at n=10A097166
- a(n) = Sum_{k=0..n} C(floor((n+1)/2),floor((k+1)/2)) * 3^k.at n=20A097169
- Numbers k such that the k-th triangular number contains only digits {1,8,9}.at n=21A119151
- a(n) = A133195(n)/3.at n=31A133201