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A271584 Irregular triangle read by rows: alternate (k-1)*k, k^2, for k = 0 to n. 1
0, 0, 0, 0, 0, 1, 0, 0, 2, 0, 1, 4, 0, 0, 2, 6, 0, 1, 4, 9, 0, 0, 2, 6, 12, 0, 1, 4, 9, 16, 0, 0, 2, 6, 12, 20, 0, 1, 4, 9, 16, 25, 0, 0, 2, 6, 12, 20, 30, 0, 1, 4, 9, 16, 25, 36, 0, 0, 2, 6, 12, 20, 30, 42, 0, 1, 4, 9, 16, 25, 36, 49 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,9

COMMENTS

This is the irregular triangle e(n) mentioned in A269837.

Last number: 0, 0, 0, 1, 2, 4, 6, 9, 12, 16, 20, 25, ... = A002620 with a third initial 0.

Row sums: 0, 0, 0, 1, 2, 5, 8, 14, 20, 30, 40, ... = A006918 with three initial 0.

Columns: the sum of the first two terms is A000384(n).

LINKS

Table of n, a(n) for n=0..71.

EXAMPLE

Irregular triangle:

0,

0,

0, 0,

0, 1,

0, 0, 2,

0, 1, 4,

0, 0, 2, 6,

0, 1, 4, 9,

0, 0, 2, 6, 12,

0, 1, 4, 9, 16,

0, 0, 2, 6, 12, 20,

0, 1, 4, 9, 16, 25,

etc.

MATHEMATICA

Flatten[Transpose /@ Table[{k (k - 1), k^2}, {n, 0, 7}, {k, 0, n}]] (* Michael De Vlieger, Apr 10 2016 *)

CROSSREFS

Cf. A000290, A000384, A002262, A006918, A161680, A269837.

Sequence in context: A257920 A258210 A258228 * A072737 A061290 A099096

Adjacent sequences:  A271581 A271582 A271583 * A271585 A271586 A271587

KEYWORD

nonn,tabf

AUTHOR

Paul Curtz, Apr 10 2016

STATUS

approved

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Last modified December 10 15:09 EST 2019. Contains 329896 sequences. (Running on oeis4.)