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

1,1

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).

Links

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

Example

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

Maple

A168218 := proc(n, m) 2*(min(n+1-m, m))^2 ; end proc:
seq(seq(A168218(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 *)

Crossrefs

Sequence in context: A066874 A087577 A323741 * A203610 A294873 A058788

Adjacent sequences: A168278 A168279 A168280 * A168282 A168283 A168284

Keyword

nonn,tabl,easy

Author

Paul Curtz, Nov 22 2009

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

Status

approved