A180955 Numerator in triangle T(n,k)=A180955/A180956 read by rows. A001790(A004736).

1, 1, 1, 3, 1, 1, 5, 3, 1, 1, 35, 5, 3, 1, 1, 63, 35, 5, 3, 1, 1, 231, 63, 35, 5, 3, 1, 1, 429, 231, 63, 35, 5, 3, 1, 1, 6435, 429, 231, 63, 35, 5, 3, 1, 1, 12155, 6435, 429, 231, 63, 35, 5, 3, 1, 1, 46189, 12155, 6435, 429, 231, 63, 35, 5, 3, 1, 1, 88179, 46189, 12155, 6435, 429

Offset

1,4

Comments

Consider the fractional triangle A180955/A180956, call it triangle A. Consider also a triangle defined by k=1: T(n,1)=1, k>1 and n>=k: T(n,k)= any random number, else 0, call it triangle B. Calculate the matrix inverse of triangle B, call it triangle C. Multiply C with A, call the result triangle D. Calculate the matrix inverse of D, call it triangle E. Then the first column in both matrix A and matrix E will have the fraction A001790/A046161 in the first column.

Links

Table of n, a(n) for n=1..71.

Example

Triangle starts:
1,
1,1,
3,1,1,
5,3,1,1,
35,5,3,1,1,
63,35,5,3,1,1,
231,63,35,5,3,1,1,
429,231,63,35,5,3,1,1,
6435,429,231,63,35,5,3,1,1,
12155,6435,429,231,63,35,5,3,1,1,
46189,12155,6435,429,231,63,35,5,3,1,1,
88179,46189,12155,6435,429,231,63,35,5,3,1,1,

Crossrefs

Cf. A180956, A001790, A046161.

Sequence in context: A131247 A114278 A134836 * A349182 A191751 A285409

Adjacent sequences: A180952 A180953 A180954 * A180956 A180957 A180958

Keyword

nonn,tabl

Author

Mats Granvik, Sep 28 2010

Status

approved