A143269 - OEIS

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A143269

Triangle read by rows, A127648 * A000012 * A130207, 1<=k<=n.

1, 2, 2, 3, 3, 6, 4, 4, 8, 8, 5, 5, 10, 10, 20, 6, 6, 12, 12, 24, 12, 7, 7, 14, 14, 28, 14, 42, 8, 8, 16, 16, 32, 16, 48, 32, 9, 9, 18, 18, 36, 18, 54, 36, 54, 10, 10, 20, 20, 40, 20, 60, 40, 60, 40, 11, 11, 22, 22, 44, 22, 66, 44, 66, 44, 110

(list; table; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

Row sums = A143270: (1, 4, 12, 24, 50, 72, 126, 176,...).

LINKS

Table of n, a(n) for n=1..66.

FORMULA

Triangle read by rows, A127648 * A000012 * A130207. T(n,k) = n*phi(k)

EXAMPLE

First few rows of the triangle =

2, 2;

3, 3, 6;

4, 4, 8, 8;

5, 5, 10, 10, 20;

6, 6, 12, 12, 24, 12;

7, 7, 14, 1428, 14, 42;

...

Row 5 = (5, 5, 10, 10, 20) = (5*1, 5*1, 5*2, 5*2, 5*4); where phi(k) = (1, 1, 2, 2, 4,...).

CROSSREFS

Cf. A000010, A143270.

Sequence in context: A240505 A372007 A051715 * A036817 A239962 A175175

Adjacent sequences: A143266 A143267 A143268 * A143270 A143271 A143272

KEYWORD

nonn,tabl

AUTHOR

Gary W. Adamson, Aug 03 2008

STATUS

approved