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A143187 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]]]]]. 0
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; refs; listen; history; text; internal format)
OFFSET
1,5
COMMENTS
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.
LINKS
FORMULA
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]]]]].
EXAMPLE
{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}
MATHEMATICA
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[%]
CROSSREFS
Sequence in context: A157415 A154325 A129765 * A348042 A143209 A163994
KEYWORD
nonn,uned
AUTHOR
STATUS
approved

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Last modified March 29 03:51 EDT 2024. Contains 371264 sequences. (Running on oeis4.)