83097
domain: N
Appears in sequences
- a(n) = Sum_{k=0..n} C(n-k,3k).at n=21A003522
- Riordan numbers: a(n) = (n-1)*(2*a(n-1) + 3*a(n-2))/(n+1).at n=15A005043
- sec(exp(x)-cos(x))=1+1/2!*x^2+6/3!*x^3+21/4!*x^4+120/5!*x^5...at n=8A013320
- Bisection of A005043.at n=7A099252
- Expansion of x/(1 - 2*x^2 - x^3 + x^4).at n=31A122514
- Triangle read by rows: T(n,k) is the number of paths in the first quadrant from (0,0) to (n,0), consisting of steps U=(1,1), D=(1,-1), h=(1,0) and H=(2,0), having k doublerises (i.e., UU's) (0 <= k <= floor(n/2) - 1 for n >= 2).at n=38A132279
- First column of A174295.at n=17A174297
- a(n) = [x^n] (1 - 2*x - sqrt((1 - 3*x)/(1 + x)))/(2*x^3).at n=13A342912
- Two-Catalan Triangle read by rows, for n>=0 and k>=0.at n=50A380912