A271668 -id:A271668 - cp's OEIS frontend

A132169 Irregular triangle read by rows. A141616(n)/4.

2, 3, 6, 4, 8, 5, 12, 10, 6, 15, 12, 7, 20, 18, 14, 8, 24, 21, 16, 9, 30, 28, 24, 18, 10, 35, 32, 27, 20, 11, 42, 40, 36, 30, 22, 12, 48, 45, 40, 33, 24, 13, 56, 54, 50, 44, 36, 26, 14, 63, 60, 55, 48, 39, 28, 15, 72, 70, 66, 60, 52, 42, 30, 16

Offset: 0

Paul Curtz, Aug 26 2008

From Paul Curtz, Apr 14 2016: (Start)
Row sums: A023856.
Even rows: A120070.
Odd rows:
2,
6,   4,
12, 10, 6,
etc.
Divided by 2:
1,
3,   2,
6,   5,  3,
10,  9,  7, 4,
15, 14, 12, 9, 5,
etc.
This is A049777. Or positive A049780.
Also A271668 without the first column and bordered by the natural numbers as main diagonal.
(End)

			Irregular triangle:
2,
3,
6,   4,
8,   5,
12, 10, 6,
15, 12, 7,
20, 18, 14,  8,
24, 21, 16,  9,
30, 28, 24, 18, 10,
35, 32, 27, 20, 11,
etc.

Cf. A023856, A049777, A049780, A052938, A120070, A131723, A141616, A168230, A198442, A271668.

(Table[n^2 - k^2, {n, 3, 18}, {k, n}] /. m_ /; Or[OddQ@ m, m == 0] -> Nothing)/4 // Flatten (* Michael De Vlieger, Apr 14 2016 *)

Edited by Charles R Greathouse IV, Nov 11 2009

cp's OEIS Frontend

A132169 Irregular triangle read by rows. A141616(n)/4.

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