

A047120


Array T read by diagonals: T(h,k)=number of paths consisting of steps from (0,0) to (h,k) such that each step has length 1 directed up or right and touches the line y=x/4 only at lattice points.


9



1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 3, 3, 1, 1, 1, 4, 6, 4, 2, 1, 1, 5, 10, 10, 6, 3, 1, 1, 6, 15, 20, 16, 6, 4, 1, 1, 7, 21, 35, 36, 22, 6, 5, 1, 1, 8, 28, 56, 71, 58, 28, 6, 6, 1, 1, 9, 36, 84, 127, 129, 86, 34, 12, 7, 1, 1, 10, 45, 120, 211, 256, 215, 120, 46, 19, 8, 1
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OFFSET

0,8


LINKS

Table of n, a(n) for n=0..77.


MATHEMATICA

T[_, 0] = 1; T[0, _] = 1; T[h_, k_] := T[h, k] = If[k1 >= h/4  k <= h/4, T[h, k1], 0] + T[h1, k];
Table[T[h  k, k], {h, 0, 11}, {k, h, 0, 1}] // Flatten (* JeanFrançois Alcover, Mar 06 2019 *)


CROSSREFS

Cf. A047089 (with y=x/2), A047100 (with y=x/3).
Sequence in context: A208891 A177767 A047030 * A096751 A293551 A099233
Adjacent sequences: A047117 A047118 A047119 * A047121 A047122 A047123


KEYWORD

nonn,tabl


AUTHOR

Clark Kimberling


STATUS

approved



