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A104881 Number triangle T(n,k)=sum{j=0..k, (n-k)^(k-j)}. 2
1, 1, 1, 1, 2, 1, 1, 3, 3, 1, 1, 4, 7, 4, 1, 1, 5, 13, 15, 5, 1, 1, 6, 21, 40, 31, 6, 1, 1, 7, 31, 85, 121, 63, 7, 1, 1, 8, 43, 156, 341, 364, 127, 8, 1, 1, 9, 57, 259, 781, 1365, 1093, 255, 9, 1, 1, 10, 73, 400, 1555, 3906, 5461, 3280, 511, 10, 1, 1, 11, 91, 585, 2801, 9331, 19531 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,5

COMMENTS

Reverse of triangle A104878. Row sums are A104879. Diagonal sums are A104882.

LINKS

Table of n, a(n) for n=0..72.

FORMULA

Number triangle T(n, k)=if(k<=n, sum{j=0..k, (n-k)^(k-j), 0)}.

EXAMPLE

Rows begin

1;

1,1;

1,2,1;

1,3,3,1;

1,4,7,4,1;

1,5,13,15,5,1;

CROSSREFS

Sequence in context: A101515 A028657 A053534 * A171699 A104878 A196863

Adjacent sequences:  A104878 A104879 A104880 * A104882 A104883 A104884

KEYWORD

easy,nonn,tabl

AUTHOR

Paul Barry, Mar 28 2005

STATUS

approved

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Last modified March 26 05:43 EDT 2019. Contains 321481 sequences. (Running on oeis4.)