A168281 - OEIS

%I #24 Jul 25 2024 08:49:19

%S 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,

%T 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,

%U 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

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

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

%C The flattened triangle is simply 2 followed by A137508.

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

%H Michael De Vlieger, <a href="/A168281/b168281.txt">Table of n, a(n) for n = 1..10011</a> (First 141 rows).

%e The table starts in row n=1 with columns 1<=m<=n as:

%e   2;

%e   2,2;

%e   2,8,2;

%e   2,8,8,2;

%e   2,8,18,8,2;

%e   2,8,18,18,8,2;

%e   ...

%p A168281 := proc(n,m) 2*(min(n+1-m,m))^2 ; end proc:

%p seq(seq(A168281(n,m),m=1..n),n=1..20) ;

%t 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 *)

%Y Cf. A005993, A099956, A137508, A106314.

%K nonn,tabl,easy

%O 1,1

%A _Paul Curtz_, Nov 22 2009

%E Rephrased all comments in terms of a triangle by _R. J. Mathar_, Nov 24 2010

%E More terms from _Michael De Vlieger_, Jul 19 2016

%E Definition corrected by _Georg Fischer_, Nov 11 2021