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A114119
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Row sums of triangle A114118.
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1
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1, 3, 5, 6, 8, 9, 11, 12, 14, 15, 17, 18, 20, 21, 23, 24, 26, 27, 29, 30, 32, 33, 35, 36, 38, 39, 41, 42, 44, 45, 47, 48, 50, 51, 53, 54, 56, 57, 59, 60, 62, 63, 65, 66, 68, 69, 71, 72, 74, 75, 77, 78, 80, 81, 83, 84, 86, 87, 89, 90, 92, 93, 95, 96, 98, 99, 101, 102, 104, 105
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Taken modulo 3 yields 1,0,2,0,2,0,2,0,2,..... a(n) is congruent to 0 or 2 mod 3 for n>0.
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LINKS
| Index to sequences with linear recurrences with constant coefficients, signature (1,1,-1).
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FORMULA
| a(n)=3*floor((n+1)/2)+2*mod(n+1, 2)-0^n; a(n)=sum{k=0..n, sum{j=0..n, C(floor((n+k+j)/3), k)C(k, floor((n+k+j)/3))}}.
G.f. 1 -x*(-3-2*x+2*x^2) / ( (1+x)*(x-1)^2 ). - R. J. Mathar, Oct 25 2011
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MATHEMATICA
| Join[{1, 3}, LinearRecurrence[{1, 1, -1}, {5, 6, 8}, 100]] (* From Vladimir Joseph Stephan Orlovsky, Jan 31 2012 *)
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CROSSREFS
| Cf. A007494, A049636, A045506.
Sequence in context: A184675 A089585 A121506 * A186324 A101358 A186223
Adjacent sequences: A114116 A114117 A114118 * A114120 A114121 A114122
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KEYWORD
| easy,nonn
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Nov 13 2005
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