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A128489 Triangle read by rows: A000012 * A126988 as infinite lower triangular matrices. 2
1, 3, 1, 6, 1, 1, 10, 3, 1, 1, 15, 3, 1, 1, 1, 21, 6, 3, 1, 1, 1, 28, 6, 3, 1, 1, 1, 1, 36, 10, 3, 3, 1, 1, 1, 1, 45, 10, 6, 3, 1, 1, 1, 1, 1, 55, 15, 6, 3, 3, 1, 1, 1, 1, 1, 66, 15, 6, 3, 3, 1, 1, 1, 1, 1, 1, 78, 21, 10, 6, 3, 3, 1, 1, 1, 1, 1, 1, 91, 21, 10, 6, 3, 3, 1, 1, 1, 1, 1, 1, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Row sums = A024916: (1, 4, 8, 15, 21, 33, ...).
LINKS
FORMULA
By columns, k=1,2,3,...; k repeated terms of the triangular series, (1, 3, 6, 10, ...) in the k-th column.
EXAMPLE
First few rows of the triangle:
1;
3, 1;
6, 1, 1;
10, 3, 1, 1;
15, 3, 1, 1, 1;
21, 6, 3, 1, 1, 1;
28, 6, 3, 1, 1, 1, 1;
36, 10, 3, 3, 1, 1, 1, 1;
45, 10, 6, 3, 1, 1, 1, 1, 1;
...
CROSSREFS
Sequence in context: A099512 A127096 A130541 * A034839 A089732 A158905
KEYWORD
nonn,tabl
AUTHOR
Gary W. Adamson, Mar 04 2007
EXTENSIONS
a(11) = 1 inserted and more terms from Georg Fischer, May 29 2023
STATUS
approved

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Last modified July 13 15:08 EDT 2024. Contains 374284 sequences. (Running on oeis4.)