227475

Appears in sequences

• Riordan numbers: a(n) = (n-1)*(2*a(n-1) + 3*a(n-2))/(n+1).at n=16A005043
• Bisection of Motzkin sums (A005043).at n=8A099251
• Expansion of (sqrt(1+3*x) + sqrt(1-x))/(2*sqrt(1-x)).at n=17A099323
• 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=44A132279
• Triangular numbers composed of only digits with line segments or both line segments and curves {1, 2, 4, 5, 7}.at n=33A247021
• Array T(n,k) of the expected value of trace(O)^(2k), where O is an n X n orthogonal matrix randomly selected according to Haar measure, read by antidiagonals.at n=52A247306
• Triangular numbers representable as x*y+x+y such that x and y are triangular numbers, x>=y>0.at n=34A259745
• Triangular numbers representable as x*y+x+y such that x and y are triangular numbers, x>=y>1.at n=28A259746
• a(n) = [x^n] (1 - 2*x - sqrt((1 - 3*x)/(1 + x)))/(2*x^3).at n=14A342912
• Array read by ascending antidiagonals: A(n, s) is the n-th s-Catalan number.at n=37A349934