A127477 Triangle T(n,k) read by rows: matrix product A054522 * A054523.

1, 2, 1, 5, 0, 2, 6, 3, 0, 2, 17, 0, 0, 0, 4, 10, 5, 4, 0, 0, 2, 37, 0, 0, 0, 0, 0, 6, 22, 11, 0, 6, 0, 0, 0, 4, 41, 0, 14, 0, 0, 0, 0, 0, 6, 34, 17, 0, 0, 8, 0, 0, 0, 0, 4, 101, 0, 0, 0, 0, 0, 0, 0, 0, 0, 10, 30, 15, 12, 10, 0, 6, 0, 0, 0, 0, 0, 4, 145, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 12, 74, 37, 0

Offset

1,2

Comments

If the two matrices A054522 and A054523 are commuted, the matrix product becomes A127478.

Links

Table of n, a(n) for n=1..94.

Formula

T(n,k) = sum_{j=k..n} A054522(n,j) * A054523(j,k).

sum_{k=1..n} T(n,k) = A057660(n) (row sums).

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

T(n,1) = A029939(n).

Example

First few rows of the triangle are:
1;
2, 1;
5, 0, 2;
6, 3, 0, 2;
17, 0, 0, 0, 4;
10, 5, 4, 0, 0, 2;
37, 0, 0, 0, 0, 0, 6;
22, 11, 0, 6, 0, 0, 0, 4;

Maple

A054522 := proc(n, k) if k = 1 then 1; elif n mod k = 0 then numtheory[phi](k) ; else 0 ; fi; end:
A054523 := proc(n, k) if k = n then 1; elif n mod k = 0 then numtheory[phi](n/k) ; else 0 ; fi; end:
A127477 := proc(n, k) add( A054522(n, j)*A054523(j, k), j=k..n) ; end: seq(seq( A127477(n, k), k=1..n), n=1..15) ;

Crossrefs

Cf. A054522, A054523, A057660, A000010, A029939.

Sequence in context: A322334 A198371 A352559 * A104505 A359479 A324185

Adjacent sequences: A127474 A127475 A127476 * A127478 A127479 A127480

Keyword

nonn,tabl,easy

Author

Gary W. Adamson, Jan 15 2007

Extensions

Converted comments to formulas, extended - R. J. Mathar, Sep 11 2009

Status

approved