A057580 and A105633 - Same?
Paul D. Hanna
pauldhanna at juno.com
Thu Apr 21 00:35:45 CEST 2005
Dear Seqfans,
Are sequences A057580 and A105633 the same?
Can anyone determine the answer to this question?
Below I describe the sequences more fully.
Thanks for any clues,
Paul
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Consider the maximal and minimal "numbers of codewords
in mixed code with 2 binary coordinates and n ternary
coordinates with Hamming distance 3", given at:
http://www.tcs.hut.fi/~pat/23.html
Among the codes listed there, we are interested in
the minimal and maximal of the numbers preceeding the ':'
in the following subset (see link for explanation):
(2,1,3)1: 1 code
(2,1,3)2: 1 code
(2,2,3)3: 2 codes
(2,2,3)4: 1 code
(2,3,3)7: 66 codes
(2,3,3)8: 14 codes
(2,3,3)9: 3 codes
(2,4,3)19: 25703 codes
(2,4,3)20: 668 codes
(2,4,3)21: 23 codes
(2,4,3)22: 2 codes
The minimal numbers are: 1,3,7,19, ?
and the maximal numbers are: 1,2,4,9,22, ?
The maximal numbers are given by: A057580
http://www.research.att.com/projects/OEIS?Anum=A057580
and I guess that the minimal numbers form A002426
(Central trinomial coefficients) offset 1.
Based on this guess, I wonder if the maximal numbers (A057580)
are also equal to A105633:
http://www.research.att.com/projects/OEIS?Anum=A105633
Sequence:
1,2,4,9,22,57,154,429,1223,3550,10455,31160,93802,284789,..
A105633 equals the row sums of triangle A105632,
where triangle A105632 is defined by:
http://www.research.att.com/projects/OEIS?Anum=A105632
1;
1,1;
2,1,1;
4,3,1,1;
9,7,4,1,1;
21,19,10,5,1,1;
51,51,31,13,6,1,1;
127,141,91,45,16,7,1,1;
323,393,276,141,61,19,8,1,1;
835,1107,834,461,201,79,22,9,1,1; ...
where:
column 0 is A001006 (Motzkin numbers)
column 1 is A002426 (Central trinomial coefficients).
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END
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