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Search: id:A061776
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| A061776 |
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Start with a single triangle; at n-th generation add a triangle at each vertex, allowing triangles to overlap; sequence gives number of triangles in n-th generation. |
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+0
3
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| 1, 3, 6, 12, 18, 30, 42, 66, 90, 138, 186, 282, 378, 570, 762, 1146, 1530, 2298, 3066, 4602, 6138, 9210, 12282, 18426, 24570, 36858, 49146, 73722, 98298, 147450, 196602, 294906, 393210, 589818, 786426, 1179642, 1572858, 2359290
(list; graph; listen)
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OFFSET
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0,2
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REFERENCES
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R. Reed, The Lemming Simulation Problem, Math. in School, 3 (#6, Nov. 1974), 5-6.
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FORMULA
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Explicit formula given in Maple line.
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MAPLE
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A061776 := proc(n) if n mod 2 = 0 then 6*(2^(n/2)-1); else 3*(2^((n-1)/2)-1)+3*(2^((n+1)/2)-1); fi; end; # for n >= 1
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CROSSREFS
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A061777 gives total population of triangles at n-th generation.
Sequence in context: A024513 A116958 A006156 this_sequence A074899 A125851 A066140
Adjacent sequences: A061773 A061774 A061775 this_sequence A061777 A061778 A061779
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KEYWORD
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nonn,nice,easy
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AUTHOR
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njas, R. K. Guy, Jun 23 2001
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