login
Triangle: T(n,k) is the partition function G(n-k,k).
1

%I #18 Dec 12 2021 22:32:02

%S 1,0,1,0,1,1,0,1,1,1,0,1,2,1,1,0,1,4,2,1,1,0,1,10,5,2,1,1,0,1,26,14,5,

%T 2,1,1,0,1,76,46,15,5,2,1,1,0,1,232,166,51,15,5,2,1,1,0,1,764,652,196,

%U 52,15,5,2,1,1,0,1,2620,2780,827,202,52,15,5,2,1,1

%N Triangle: T(n,k) is the partition function G(n-k,k).

%C See entries for A001680 and A001681 for appropriate references.

%H Alois P. Heinz, <a href="/A108947/b108947.txt">Rows n = 0..140, flattened</a>

%F E.g.f. for sequence G(0, k), G(1, k), ... is exp(x + (1/2)*x^2 + ... + (1/k!)*x^k).

%p G:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,

%p add(G(n-i*j, i-1)*n!/i!^j/(n-i*j)!/j!, j=0..n/i)))

%p end:

%p T:= (n, k)-> G(n-k, k):

%p seq(seq(T(n, k), k=0..n), n=0..12); # _Alois P. Heinz_, Sep 15 2013

%t G[n_, i_] := G[n, i] = If[n == 0, 1, If[i<1, 0, Sum[G[n-i*j, i-1]*n!/i!^j/(n-i*j)! /j!, {j, 0, n/i}]]]; T[n_, k_] := G[n-k, k]; Table[Table[T[n, k], {k, 0, n}], {n, 0, 12}] // Flatten (* _Jean-François Alcover_, Feb 24 2015, after _Alois P. Heinz_ *)

%Y Cf. A000110. First differences of a sequence G(k, 0), G(k, 1), ... give a row of A080510 (e.g., 0, 1, 10, 14, 15, 15, ... gives 1, 9, 4, 1).

%K easy,nonn,tabl

%O 0,13

%A _Paul Boddington_, Jul 21 2005

%E One term corrected by _Alois P. Heinz_, Sep 15 2013