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A113127
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Expansion of (1+x+x^2+x^3)/(1-x)^2.
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4
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1, 3, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50, 54, 58, 62, 66, 70, 74, 78, 82, 86, 90, 94, 98, 102, 106, 110, 114, 118, 122, 126, 130, 134, 138, 142, 146, 150, 154, 158, 162, 166, 170, 174, 178, 182, 186, 190, 194, 198, 202, 206, 210, 214, 218, 222, 226, 230
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Row sums of number triangle A113126.
Equals binomial transform of [1, 2, 1, 0, -1, 2, -3, 4, -5,...]. [From Gary W. Adamson (qntmpkt(AT)yahoo.com), Feb 14 2009]
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FORMULA
| a(n)=4n-2+2*C(0, n)+C(1, n); a(n)=C(n+1, n)+C(n, n-1)+C(n-1, n-2)+C(n-2, n-3).
Row sums of triangle A131034: (1; 2,1; 4,1,1; 6,2,1,1;...). - Gary W. Adamson (qntmpkt(AT)yahoo.com), Jun 10 2007
G.f.: (1-x^4)/(1-x)^3 [From Jaume Oliver Lafont (joliverlafont(AT)gmail.com), Mar 27 2009]
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CROSSREFS
| Cf. A016825, A073760.
Cf. A131034.
a(n)-a(n-1)=A158411(n+1) [From Jaume Oliver Lafont (joliverlafont(AT)gmail.com), Mar 27 2009]
Sequence in context: A134535 A078060 A022764 * A145913 A130246 A167381
Adjacent sequences: A113124 A113125 A113126 * A113128 A113129 A113130
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KEYWORD
| easy,nonn
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Oct 14 2005
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