

A253902


Write numbers 1, then 2^2 down to 1, then 3^2 down to 1, then 4^2 down to 1 and so on.


1



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
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OFFSET

1,2


COMMENTS

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


LINKS

Table of n, a(n) for n=1..65.


FORMULA

For 1 <= n <= 650, a(n) = n + (t + 2)*(2*t^2  t + 3)/6, where t = floor((3*n)^(1/3)+1/2).


EXAMPLE

From Omar E. Pol, Jan 20 2015: (Start)
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)


MATHEMATICA

a253902[n_] := Flatten@ Table[Reverse[Range[i^2]], {i, n}]; a253902[6] (* Michael De Vlieger, Jan 19 2015 *)


PROG

(PARI) lista(nn=10) = {for (n=1, nn, forstep(k=n^2, 1, 1, print1(k, ", "); ); ); } \\ Michel Marcus, Jan 20 2015


CROSSREFS

Cf. A064866, A074279.
Sequence in context: A113778 A295673 A155172 * A129154 A055115 A294280
Adjacent sequences: A253899 A253900 A253901 * A253903 A253904 A253905


KEYWORD

nonn,easy,tabf


AUTHOR

Mikael Aaltonen, Jan 18 2015


STATUS

approved



