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A127749 Inverse of number triangle A(n,k)=if(k<=n,if(n<=2k,1/(2n+1),0),0). +0
2
1, 0, 3, 0, -3, 5, 0, 3, -5, 7, 0, 0, 0, -7, 9, 0, -3, 5, 0, -9, 11, 0, 0, 0, 0, 0, -11, 13, 0, 3, -5, 7, 0, 0, -13, 15, 0, 0, 0, 0, 0, 0, 0, -15, 17, 0, 0, 0, -7, 9, 0, 0, 0, -17, 19, 0, 0, 0, 0, 0, 0, 0, 0, 0, -19, 21, 0, -3, 5 (list; table; graph; listen)
OFFSET

0,3

COMMENT

Conjectures: row sums modulo 2 are the Fredholm-Rueppel sequence A036987; row sums of triangle modulo 2 are A111982. Row sums are A127750.

EXAMPLE

Triangle begins

1,

0, 3,

0, -3, 5,

0, 3, -5, 7,

0, 0, 0, -7, 9,

0, -3, 5, 0, -9, 11,

0, 0, 0, 0, 0, -11, 13,

0, 3, -5, 7, 0, 0, -13, 15,

0, 0, 0, 0, 0, 0, 0, -15, 17,

0, 0, 0, -7, 9, 0, 0, 0, -17, 19,

0, 0, 0, 0, 0, 0, 0, 0, 0, -19, 21,

0, -3, 5, 0, -9, 11, 0, 0, 0, 0, -21, 23,

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -23, 25

Inverse of triangle

1,

0, 1/3,

0, 1/5, 1/5,

0, 0, 1/7, 1/7,

0, 0, 1/9, 1/9, 1/9,

0, 0, 0, 1/11, 1/11, 1/11,

0, 0, 0, 1/13, 1/13, 1/13, 1/13,

0, 0, 0, 0, 1/15, 1/15, 1/15, 1/15,

0, 0, 0, 0, 1/17, 1/17, 1/17, 1/17, 1/17,

0, 0, 0, 0, 0, 1/19, 1/19, 1/19, 1/19, 1/19,

0, 0, 0, 0, 0, 1/21, 1/21, 1/21, 1/21, 1/21, 1/21

CROSSREFS

Cf. A111967.

Sequence in context: A073367 A111862 A060858 this_sequence A138188 A014715 A131656

Adjacent sequences: A127746 A127747 A127748 this_sequence A127750 A127751 A127752

KEYWORD

sign,tabl

AUTHOR

Paul Barry (pbarry(AT)wit.ie), Jan 28 2007

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Last modified November 27 22:38 EST 2009. Contains 167602 sequences.


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