login
Triangle read by rows, formed from product of Pascal's triangle (A007318) and Aitken's (or Bell's) triangle (A011971).
1

%I #6 Mar 28 2015 18:16:21

%S 1,2,2,5,7,5,15,22,25,15,52,74,97,97,52,203,277,372,449,411,203,877,

%T 1154,1524,1948,2209,1892,877,4140,5294,6816,8734,10718,11570,9402,

%U 4140,21147,26441,33255,41954,52357,62107,64404,50127,21147,115975,142416

%N Triangle read by rows, formed from product of Pascal's triangle (A007318) and Aitken's (or Bell's) triangle (A011971).

%C These triangles are to be thought of as infinite lower-triangular matrices.

%e Triangle begins:

%e 1

%e 2 2

%e 5 7 5

%e 15 22 25 15

%e 52 74 97 97 52

%e 203 277 372 449 411 203

%t a[0, 0] = 1; a[n_, 0] := a[n - 1, n - 1]; a[n_, k_] := a[n, k] = If[k < n + 1, a[n, k - 1] + a[n - 1, k - 1], 0]; p[n_, r_] := If[r <= n + 1, Binomial[n, r], 0]; am = Table[ a[n, r], {n, 0, 9}, {r, 0, 9}]; pm = Table[p[n, r], {n, 0, 9}, {r, 0, 9}]; t = Flatten[pm.am]; Delete[ t, Position[t, 0]] (* _Robert G. Wilson v_, Jul 12 2004 *)

%Y Cf. A007318, A011971, A095675. Row sums give A005494. First column is A000110.

%K nonn,tabl,easy

%O 0,2

%A _N. J. A. Sloane_, based on a suggestion from _Gary W. Adamson_, Jun 22 2004

%E More terms from _Robert G. Wilson v_, Jul 13 2004