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A285595 Sum T(n,k) of the k-th entries in all blocks of all set partitions of [n]; triangle T(n,k), n>=1, 1<=k<=n, read by rows. 8
1, 4, 2, 17, 10, 3, 76, 52, 18, 4, 362, 274, 111, 28, 5, 1842, 1500, 675, 200, 40, 6, 9991, 8614, 4185, 1380, 325, 54, 7, 57568, 51992, 26832, 9568, 2510, 492, 70, 8, 351125, 329650, 178755, 67820, 19255, 4206, 707, 88, 9, 2259302, 2192434, 1239351, 494828, 149605, 35382, 6629, 976, 108, 10 (list; table; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
T(n,k) is also k times the number of blocks of size >k in all set partitions of [n+1]. T(3,2) = 10 = 2 * 5 because there are 5 blocks of size >2 in all set partitions of [4], namely in 1234, 123|4, 124|3, 134|2, 1|234.
LINKS
FORMULA
T(n,k) = k * Sum_{j=k+1..n+1} binomial(n+1,j)*A000110(n+1-j).
T(n,k) = k * Sum_{j=k+1..n+1} A175757(n+1,j).
Sum_{k=1..n} T(n,k)/k = A278677(n+1).
EXAMPLE
T(3,2) = 10 because the sum of the second entries in all blocks of all set partitions of [3] (123, 12|3, 13|2, 1|23, 1|2|3) is 2+2+3+3+0 = 10.
Triangle T(n,k) begins:
: 1;
: 4, 2;
: 17, 10, 3;
: 76, 52, 18, 4;
: 362, 274, 111, 28, 5;
: 1842, 1500, 675, 200, 40, 6;
: 9991, 8614, 4185, 1380, 325, 54, 7;
: 57568, 51992, 26832, 9568, 2510, 492, 70, 8;
MAPLE
T:= proc(h) option remember; local b; b:=
proc(n, l) option remember; `if`(n=0, [1, 0],
(p-> p+[0, (h-n+1)*p[1]*x^1])(b(n-1, [l[], 1]))+
add((p-> p+[0, (h-n+1)*p[1]*x^(l[j]+1)])(b(n-1,
sort(subsop(j=l[j]+1, l), `>`))), j=1..nops(l)))
end: (p-> seq(coeff(p, x, i), i=1..n))(b(h, [])[2])
end:
seq(T(n), n=1..12);
# second Maple program:
b:= proc(n) option remember; `if`(n=0, [1, 0],
add((p-> p+[0, p[1]*add(x^k, k=1..j-1)])(
b(n-j)*binomial(n-1, j-1)), j=1..n))
end:
T:= n-> (p-> seq(coeff(p, x, i)*i, i=1..n))(b(n+1)[2]):
seq(T(n), n=1..12);
MATHEMATICA
b[n_] := b[n] = If[n == 0, {1, 0}, Sum[# + {0, #[[1]]*Sum[x^k, {k, 1, j-1} ]}&[b[n - j]*Binomial[n - 1, j - 1]], {j, 1, n}]];
T[n_] := Table[Coefficient[#, x, i]*i, {i, 1, n}] &[b[n + 1][[2]]];
Table[T[n], {n, 1, 12}] // Flatten (* Jean-François Alcover, May 23 2018, translated from 2nd Maple program *)
CROSSREFS
Column k=1 gives A124325(n+1).
Row sums give A000110(n) * A000217(n) = A105488(n+3).
Main diagonal and first lower diagonal give: A000027, A028552.
Sequence in context: A189741 A303142 A328695 * A255566 A371210 A302461
KEYWORD
nonn,tabl
AUTHOR
Alois P. Heinz, Apr 22 2017
STATUS
approved

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Last modified March 28 18:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)