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A180955 Numerator in triangle T(n,k)=A180955/A180956 read by rows. A001790(A004736). 2
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 (list; table; graph; refs; listen; history; text; internal format)
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 * A191751 A285409 A208510

Adjacent sequences:  A180952 A180953 A180954 * A180956 A180957 A180958

KEYWORD

nonn,tabl

AUTHOR

Mats Granvik, Sep 28 2010

STATUS

approved

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Last modified October 17 14:47 EDT 2019. Contains 328114 sequences. (Running on oeis4.)