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Search: id:A111074
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| A111074 |
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Let t(n) denote the triangular numbers (A000217). Sequence mixes t(n+2) and t(n). |
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+0
1
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| 3, 0, 6, 1, 10, 3, 15, 6, 21, 10, 28, 15, 36, 21, 45, 28, 55, 36, 66, 45, 78, 55, 91, 66, 105, 78, 120, 91, 136, 105, 153, 120, 171, 136, 190, 153, 210, 171, 231, 190, 253, 210, 276, 231, 300, 253, 325, 276, 351, 300, 378, 325, 406, 351, 435, 378, 465, 406, 496, 435
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OFFSET
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0,1
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FORMULA
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G.f.: (3-3x+x^3)/((1-x)(1-x^2)^2); a(n)=a(n-1)+2a(n-2)-2a(n-3)-a(n-4)+a(n-5); - Paul Barry (pbarry(AT)wit.ie), Mar 22 2006
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MATHEMATICA
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Flatten[ Table[{(n + 2)(n + 3)/2, n(n + 1)/2}, {n, 0, 29}]] (* Robert G. Wilson v *)
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CROSSREFS
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Cf. mix of t(n+1) and t(n): A008795.
Adjacent sequences: A111071 A111072 A111073 this_sequence A111075 A111076 A111077
Sequence in context: A022899 A081978 A117784 this_sequence A007384 A077574 A071126
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KEYWORD
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easy,nonn
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AUTHOR
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Stuart M. Ellerstein (ellerstein(AT)aol.com), Oct 10 2005
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(at)rgwv.com), Oct 11 2005
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