A103690 - OEIS

A103690

Triangle read by rows: T(n,k)=binomial(n,k-1)*k^(k-1)*(n+1-k)^(n-k) (1<=k<=n).

1, 2, 4, 9, 12, 27, 64, 72, 108, 256, 625, 640, 810, 1280, 3125, 7776, 7500, 8640, 11520, 18750, 46656, 117649, 108864, 118125, 143360, 196875, 326592, 823543, 2097152, 1882384, 1959552, 2240000, 2800000, 3919104, 6588344, 16777216, 43046721

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OFFSET

1,2

REFERENCES

I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, Wiley, N.Y., 1983,(p.27, Problem 1.2.6 (b)).

LINKS

Table of n, a(n) for n=1..37.

FORMULA

T(n, k)=binomial(n, k-1)*k^(k-1)*(n+1-k)^(n-k) (1<=k<=n).

MAPLE

T:=proc(n, k) if k<=n then binomial(n, k-1)*k^(k-1)*(n+1-k)^(n-k) else 0 fi end: for n from 1 to 9 do seq(T(n, k), k=1..n) od; # yields sequence in triangular form

CROSSREFS

Row sums yield A053506. T(n, 1)=A000169(n). T(n, n)=A000312(n).

Sequence in context: A282456 A176472 A139557 * A098009 A129376 A266582

Adjacent sequences: A103687 A103688 A103689 * A103691 A103692 A103693

KEYWORD

nonn,tabl

AUTHOR

Emeric Deutsch, Mar 27 2005

STATUS

approved