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A134234
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Triangle read by rows, n-th row = n terms of 2n, 2n+2, 2n+4, ..., 1; with a(1) = 1.
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3
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1, 4, 1, 6, 8, 1, 8, 10, 12, 1, 10, 12, 14, 16, 1, 12, 14, 16, 18, 20, 1, 14, 16, 18, 20, 22, 24, 1, 16, 18, 20, 22, 24, 26, 28, 1, 18, 20, 22, 24, 26, 28, 30, 32, 1, 20, 22, 24, 26, 28, 30, 32, 34, 36, 1
(list;
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graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,2
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COMMENTS
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Row sums = A056108: (1, 5, 15, 31, 53, ...).
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LINKS
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Robert Israel, Table of n, a(n) for n = 1..10011
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FORMULA
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G.f.: 2*x/(1-x)^2 - 2*(2-x)/(1-x)*Sum_{n>=1} n*x^(n*(n+1)/2) + (3-x)/(1-x)*Sum_{n>=1} x^(n*(n+1)/2). - Robert Israel, Jan 15 2016
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EXAMPLE
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First few rows of the triangle:
1;
4, 1;
6, 8, 1;
8, 10, 12, 1;
10, 12, 14, 16, 1;
...
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MAPLE
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seq(op([seq(2*n+2*k, k=0..n-2), 1]), n=1..10); # Robert Israel, Jan 15 2016
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MATHEMATICA
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Flatten[Table[Join[{1}, Range[n, 2n-3, 2]], {n, 4, 30, 2}]] (* Harvey P. Dale, Nov 06 2013 *)
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CROSSREFS
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Cf. A056108.
Sequence in context: A214561 A066575 A070251 * A207628 A350106 A205137
Adjacent sequences: A134231 A134232 A134233 * A134235 A134236 A134237
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KEYWORD
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nonn,tabl
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AUTHOR
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Gary W. Adamson, Oct 14 2007
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STATUS
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approved
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