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A253902
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Write numbers 1, then 2^2 down to 1, then 3^2 down to 1, then 4^2 down to 1 and so on.
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1
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1, 4, 3, 2, 1, 9, 8, 7, 6, 5, 4, 3, 2, 1, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 36, 35, 34, 33, 32, 31, 30, 29, 28, 27
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,2
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COMMENTS
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Triangle read by rows in which row n lists the first n^2 positive integers in decreasing order, n >= 1. - Omar E. Pol, Jan 20 2015
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LINKS
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FORMULA
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For 1 <= n <= 650, a(n) = -n + (t + 2)*(2*t^2 - t + 3)/6, where t = floor((3*n)^(1/3)+1/2).
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EXAMPLE
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Written as an irregular triangle in which row lengths are successive squares, the sequence begins:
1;
4, 3, 2, 1;
9, 8, 7, 6, 5, 4, 3, 2, 1;
16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1;
...
(End)
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MATHEMATICA
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a253902[n_] := Flatten@ Table[Reverse[Range[i^2]], {i, n}]; a253902[6] (* Michael De Vlieger, Jan 19 2015 *)
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PROG
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(PARI) lista(nn=10) = {for (n=1, nn, forstep(k=n^2, 1, -1, print1(k, ", "); ); ); } \\ Michel Marcus, Jan 20 2015
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CROSSREFS
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KEYWORD
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nonn,easy,tabf
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AUTHOR
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STATUS
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approved
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