login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual appeal: Please make a donation to keep the OEIS running! Over 6000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A127476 Triangle T(n,k) = sum_{j=k..n, gcd(n,j)=1, k|j} phi(k). 0
1, 1, 0, 2, 1, 0, 2, 0, 2, 0, 4, 2, 2, 2, 0, 2, 0, 0, 0, 4, 0, 6, 3, 4, 2, 4, 2, 0, 4, 0, 2, 0, 4, 0, 6, 0, 6, 3, 0, 4, 4, 0, 6, 4, 0, 4, 0, 4, 0, 0, 0, 6, 0, 6, 0, 10, 5, 6, 4, 8, 2, 6, 4, 6, 4, 0, 4, 0, 0, 0, 4, 0, 6, 0, 0, 0, 10, 0 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..78.

FORMULA

T(n,k) = sum_{j=k..n} A054521(n,j) * A054522(j,k), product of the two infinite lower triangular matrices.

T(n,1) = A000010(n).

EXAMPLE

First few rows of the triangle are:

1;

1, 0;

2, 1, 0;

2, 0, 2, 0;

4, 2, 2, 2, 0;

2, 0, 0, 0, 4, 0;

6, 3, 4, 2, 4, 2, 0;

4, 0, 2, 0, 4, 0, 6, 0;

...

CROSSREFS

Cf. A054521, A054522, A023896 (row sums), A000010.

Sequence in context: A244553 A231167 A194313 * A140397 A120614 A287516

Adjacent sequences:  A127473 A127474 A127475 * A127477 A127478 A127479

KEYWORD

nonn,tabl

AUTHOR

Gary W. Adamson, Jan 15 2007

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified November 18 19:06 EST 2017. Contains 294894 sequences.