A168281 Triangle T(n,m) = 2*(min(n - m + 1, m))^2 read by rows.

2, 2, 2, 2, 8, 2, 2, 8, 8, 2, 2, 8, 18, 8, 2, 2, 8, 18, 18, 8, 2, 2, 8, 18, 32, 18, 8, 2, 2, 8, 18, 32, 32, 18, 8, 2, 2, 8, 18, 32, 50, 32, 18, 8, 2, 2, 8, 18, 32, 50, 50, 32, 18, 8, 2, 2, 8, 18, 32, 50, 72, 50, 32, 18, 8, 2, 2, 8, 18, 32, 50, 72, 72, 50, 32, 18, 8, 2, 2, 8, 18, 32, 50, 72, 98, 72

Offset: 1

Author

Paul Curtz, Nov 22 2009

Keywords

• nonn
• tabl
• easy

Comments

Row sums are A099956(n-1) = 2*A005993(n-1).

The flattened triangle is simply 2 followed by A137508.

If A106314 is interpreted as a triangle, T(n,m) = 2*A106314(n,m).

Examples

			The table starts in row n=1 with columns 1<=m<=n as:
  2;
  2,2;
  2,8,2;
  2,8,8,2;
  2,8,18,8,2;
  2,8,18,18,8,2;
  ...
		

Links

• Michael De Vlieger, Table of n, a(n) for n = 1..10011 (First 141 rows).

Crossrefs

Cf. A005993, A099956, A137508, A106314.

Programs

Maple

A168281 := proc(n,m) 2*(min(n+1-m,m))^2 ; end proc:
seq(seq(A168281(n,m),m=1..n),n=1..20) ;

Mathematica

Table[Map[2 Min[n + # - 1, #]^2 &, Drop[#, -Boole@ EvenQ@ n] ~Join~ Reverse@ # &@ Range@ Floor[n/2]], {n, 2, 14}] // Flatten (* Michael De Vlieger, Jul 19 2016 *)

Extensions

Rephrased all comments in terms of a triangle by R. J. Mathar, Nov 24 2010

More terms from Michael De Vlieger, Jul 19 2016

Definition corrected by Georg Fischer, Nov 11 2021