Number of n X 4 arrays with each row a permutation of 1..4 having at least as many downsteps as the preceding row, with rows in lexicographically nondecreasing order.

A222156

Number of n X 4 arrays with each row a permutation of 1..4 having at least as many downsteps as the preceding row, with rows in lexicographically nondecreasing order.

Terms

    a(0) =24a(1) =277a(2) =2132a(3) =12521a(4) =60344a(5) =249641a(6) =913748a(7) =3023603a(8) =9190984a(9) =25981835a(10) =68967340a(11) =173242095a(12) =414433320a(13) =949144335a(14) =2090284620a(15) =4443280530a(16) =9145850640a(17) =18279915390a(18) =35563612920a(19) =67490348310a(20) =125168633040a(21) =227242504470

External references