3342081

Appears in sequences

• Number of distributive lattices; also number of paths with n turns when light is reflected from 4 glass plates.at n=14A006357
• Bottom line of 4-wave sequence A038197, also bisection of A006357.at n=7A038235
• T(n,k)=Number of nXk 0..3 arrays with antidiagonals unimodal and rows and diagonals nondecreasing.at n=34A223961
• Number of 7Xn 0..3 arrays with antidiagonals unimodal and rows and diagonals nondecreasing.at n=1A223967
• Expansion of x - 1/(x - 1/(x - 1/(x - 1/(x + 1)))).at n=14A373568
• a(n) = 1 + Sum_{k=1..n, j=1..k} binomial(n,k)*binomial(n,j)*|Stirling_1(k,j)|*j!.at n=7A376766