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Search: id:A115281
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| A115281 |
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Correlation triangle for the sequence 2-0^n. |
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+0
1
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| 1, 2, 2, 2, 5, 2, 2, 6, 6, 2, 2, 6, 9, 6, 2, 2, 6, 10, 10, 6, 2, 2, 6, 10, 13, 10, 6, 2, 2, 6, 10, 14, 14, 10, 6, 2, 2, 6, 10, 14, 17, 14, 10, 6, 2, 2, 6, 10, 14, 18, 18, 14, 10, 6, 2, 2, 6, 10, 14, 18, 21, 18, 14, 10
(list; table; graph; listen)
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OFFSET
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0,2
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COMMENT
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Row sums are (n+1)^2 (A000290(n+1)). Diagonal sums are the Molien series A007980. T(2n,n) is 4n+1 (A016813), the partial sums of (2-0^n)^2. T(2,n)-T(2n,n+1) is 3-2*0^n.
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FORMULA
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G.f.: (1+x)(1+x*y)/((1-x)(1-x*y)(1-x^2*y)); Number triangle T(n, k)=sum{j=0..n, [j<=k]*(2-0^(k-j))*[j<=n-k]*(2-0^(n-k-j))}.
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EXAMPLE
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Triangle begins
1;
2,2;
2,5,2;
2,6,6,2;
2,6,9,6,2;
2,6,10,10,6,2;
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CROSSREFS
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Sequence in context: A088885 A121358 A112659 this_sequence A130155 A113516 A120642
Adjacent sequences: A115278 A115279 A115280 this_sequence A115282 A115283 A115284
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KEYWORD
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easy,nonn,tabl
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Jan 19 2006
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