13335840

Appears in sequences

• Triangle of coefficients in expansion of D^n (sec x) / sec x in powers of tan x.at n=33A008294
• Triangle read by rows: T(n,k) = value of (d^2n/dx^2n) (tan^(2k)(x)/cos(x)) at the point x = 0.at n=18A151775
• Numbers k for which k = sigma(sigma(x)) = sigma(sigma(y)) for some x and y such that k = x + y.at n=14A229953
• Triangle read by rows: T(n,k) (n>=1, 4<=k<=n+3) is the number of k-sequences of balls colored with at most n colors such that exactly three balls are of a color seen previously in the sequence.at n=26A292879
• T(n,n-5), where T(*,*) is A350970.at n=6A350973
• Expansion of e.g.f. exp( (x * (1+x))^2 ).at n=10A361570
• Triangle read by rows: T(n,m) (1<=m<=n) = number of surjections f:[n]->[m] with f(n) != f(j), j<n.at n=51A380977