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A127471
Triangle formed from the matrix product A051731 * A054522 of infinite lower triangular matrices, read by rows.
1
1, 2, 1, 2, 0, 2, 3, 2, 0, 2, 2, 0, 0, 0, 4, 4, 2, 4, 0, 0, 2, 2, 0, 0, 0, 0, 0, 6, 4, 3, 0, 4, 0, 0, 0, 4, 3, 0, 4, 0, 0, 0, 0, 0, 6, 4, 2, 0, 0, 8, 0, 0, 0, 0, 4, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 10, 6, 4, 6, 4, 0, 4, 0, 0, 0, 0, 0, 4, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 12
OFFSET
1,2
COMMENTS
Left column = (1, 2, 2, 3, 2, 4, ...) = d(n), A000005; right border = (1, 1, 2, 2, 4, 2, 6, ...) = phi(n), A000010; row sums = (1, 3, 4, 7, 6, 12, ...) = sigma(n), A000203.
EXAMPLE
First few rows of the triangle:
1;
2, 1;
2, 0, 2;
3, 2, 0, 2;
2, 0, 0, 0, 4;
4, 2, 4, 0, 0, 2;
2, 0, 0, 0, 0, 0, 6;
4, 3, 0, 4, 0, 0, 0, 4;
3, 0, 4, 0, 0, 0, 0, 0, 6;
4, 2, 0, 0, 8, 0, 0, 0, 0, 4;
...
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Gary W. Adamson, Jan 15 2007
EXTENSIONS
Edited by N. J. A. Sloane, Aug 11 2019
a(49) = 0 inserted and more terms from Georg Fischer, May 29 2023
STATUS
approved