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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, 8, 0, 0, 0, 0, 4 (list; table; graph; refs; listen; history; text; internal format)
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.

LINKS

Table of n, a(n) for n=1..54.

EXAMPLE

First few rows of the triangle are:

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

Cf. A054522, A051731, A000005, A000203, A000010.

Sequence in context: A335904 A144736 A137423 * A309044 A240312 A339898

Adjacent sequences:  A127468 A127469 A127470 * A127472 A127473 A127474

KEYWORD

nonn,tabl

AUTHOR

Gary W. Adamson, Jan 15 2007

EXTENSIONS

Edited by N. J. A. Sloane, Aug 11 2019

STATUS

approved

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Last modified August 1 14:14 EDT 2021. Contains 346391 sequences. (Running on oeis4.)