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Search: id:A143187
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| A143187 |
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A symmetrical triangle sequence with low, even center: t(n,m)=If[(n - m)*m == 0, 1, If[m <= Floor[n/2] && Mod[m, 2] == 1, 2*m, If[m <= Floor[n/2] && Mod[m, 2] == 0, m, If[m > Floor[n/2] && Mod[n - m, 2] == 1, 2*(n - m), If[m > Floor[n/2] && Mod[n - m, 2] == 0, (n - m), n - m]]]]]. |
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+0
1
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| 1, 1, 1, 1, 2, 1, 1, 2, 2, 1, 1, 2, 2, 2, 1, 1, 2, 2, 2, 2, 1, 1, 2, 2, 6, 2, 2, 1, 1, 2, 2, 6, 6, 2, 2, 1, 1, 2, 2, 6, 4, 6, 2, 2, 1, 1, 2, 2, 6, 4, 4, 6, 2, 2, 1, 1, 2, 2, 6, 4, 10, 4, 6, 2, 2, 1
(list; graph; listen)
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OFFSET
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1,5
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COMMENT
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Row sums are:
{1, 2, 4, 6, 8, 10, 16, 22, 26, 30, 40}.
There are two design feature here:
1) modulo 2 hollow center
2) very low row sum.
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FORMULA
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t(n,m)=If[(n - m)*m == 0, 1, If[m <= Floor[n/2] && Mod[m, 2] == 1, 2*m, If[m <= Floor[n/2] && Mod[m, 2] == 0, m, If[m > Floor[n/2] && Mod[n - m, 2] == 1, 2*(n - m), If[m > Floor[n/2] && Mod[n - m, 2] == 0, (n - m), n - m]]]]].
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EXAMPLE
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{1},
{1, 1},
{1, 2, 1},
{1, 2, 2, 1},
{1, 2, 2, 2, 1},
{1, 2, 2, 2, 2, 1},
{1, 2, 2, 6, 2, 2, 1},
{1, 2, 2, 6, 6, 2, 2, 1},
{1, 2, 2, 6, 4, 6, 2, 2, 1},
{1, 2, 2, 6, 4, 4, 6, 2, 2, 1},
{1, 2, 2, 6, 4, 10, 4, 6, 2, 2, 1}
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MATHEMATICA
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Clear[t, n, m]; t[n_, m_] = If[(n - m)*m == 0, 1, If[m <= Floor[n/2] && Mod[m, 2] == 1, 2*m, If[m <= Floor[n/2] && Mod[m, 2] == 0, m, If[m > Floor[n/2] && Mod[n - m, 2] == 1, 2*(n - m), If[m > Floor[n/2] && Mod[n - m, 2] == 0, (n - m), n - m]]]]]; Table[Table[t[n, m], {m, 0, n}], {n, 0, 10}]; Flatten[%]
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CROSSREFS
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Sequence in context: A157415 A154325 A129765 this_sequence A143209 A163994 A156593
Adjacent sequences: A143184 A143185 A143186 this_sequence A143188 A143189 A143190
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KEYWORD
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nonn,uned
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AUTHOR
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Roger L. Bagula and Gary W. Adamson (rlbagulatftn(AT)yahoo.com), Oct 17 2008
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