A124975 - OEIS

A124975

Table (read by antidiagonals): t(1,n) = t(m,1) = 1 for all m and n. t(m,n) = (product{k=1 to m-1} t(k,n)) + (product{k=1 to n-1} t(m,k)).

1, 1, 1, 1, 2, 1, 1, 3, 3, 1, 1, 7, 6, 7, 1, 1, 43, 25, 25, 43, 1, 1, 1807, 493, 350, 493, 1807, 1, 1, 3263443, 223657, 82449, 82449, 223657, 3263443, 1, 1, 10650056950807, 49621568893, 5454149449, 3495672702, 5454149449, 49621568893

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OFFSET

1,5

LINKS

Table of n, a(n) for n=1..43.

EXAMPLE

t(3,4) = t(1,4)*t(2,4) + t(3,1)*t(3,2)*t(3,3) = 1*7 + 1*3*6 = 25.

MATHEMATICA

t[m_, n_] := t[m, n] = If[m == 1 || n == 1, 1, Product[t[k, n], {k, m - 1}] + Product[t[m, j], {j, n - 1}]]; Flatten@Table[t[d + 1 - j, j], {d, 9}, {j, d}] (* Ray Chandler, Nov 19 2006 *)

CROSSREFS

Cf. A124976.

Sequence in context: A215297 A225910 A215292 * A171246 A129439 A176469

Adjacent sequences: A124972 A124973 A124974 * A124976 A124977 A124978

KEYWORD

easy,nonn,tabl

AUTHOR

Leroy Quet, Nov 14 2006

EXTENSIONS

Extended by Ray Chandler, Nov 19 2006

STATUS

approved