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A127779 Triangle read by rows: A004736 * A127773. 1
1, 2, 3, 3, 6, 6, 4, 9, 12, 10, 5, 12, 18, 20, 15, 6, 15, 24, 30, 30, 21, 7, 18, 30, 40, 45, 42, 28, 8, 21, 36, 50, 60, 63, 56, 36, 9, 24, 42, 60, 75, 84, 84, 72, 45 (list; table; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Row sums = bin(n,4), (A000332): (1, 5, 15, 35, ...).
From Clark Kimberling, Sep 16 2008: (Start)
As a rectangular array: R = A000027*A000217; R(m,n) = n*binomial(m+1,2).
R is the accumulation array (cf. A144112) of A002260 (rectangular, with n-th row (n,n,n,n,...). (End)
As a rectangular array read by ascending antidiagonals, T(n,k) is the total number of triangles obtained when a triangle is cut into n parts with segments going down from the apex to its base and into k parts with segments parallel to its base. See Quora link. - Michel Marcus, Apr 07 2023
LINKS
FORMULA
A004736 * A127773 as infinite lower triangular matrices.
EXAMPLE
First few rows of the triangle:
1;
2, 3;
3, 6, 6;
4, 9, 12, 10;
5, 12, 18, 20, 15;
6, 15, 24, 30, 30, 21;
7, 18, 30, 40, 45, 42, 28;
...
First few rows of the rectangular array:
1 3 6 10 15 ...
2 6 12 20 30 ...
3 9 18 30 45 ...
4 12 24 40 60 ...
5 15 30 50 75 ...
...
CROSSREFS
Cf. A002260. - Clark Kimberling, Sep 16 2008
Sequence in context: A075258 A321745 A212629 * A207634 A222862 A101437
KEYWORD
nonn,tabl
AUTHOR
Gary W. Adamson, Jan 28 2007
STATUS
approved

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Last modified April 16 01:01 EDT 2024. Contains 371696 sequences. (Running on oeis4.)