A134234 Triangle read by rows, n-th row = n terms of 2n, 2n+2, 2n+4, ..., 1; with a(1) = 1.

1, 4, 1, 6, 8, 1, 8, 10, 12, 1, 10, 12, 14, 16, 1, 12, 14, 16, 18, 20, 1, 14, 16, 18, 20, 22, 24, 1, 16, 18, 20, 22, 24, 26, 28, 1, 18, 20, 22, 24, 26, 28, 30, 32, 1, 20, 22, 24, 26, 28, 30, 32, 34, 36, 1

Offset: 1

Author

Gary W. Adamson, Oct 14 2007

Keywords

• nonn
• tabl

Comments

Row sums = A056108: (1, 5, 15, 31, 53, ...).

Examples

			First few rows of the triangle:
   1;
   4,  1;
   6,  8,  1;
   8, 10, 12,  1;
  10, 12, 14, 16, 1;
  ...
		

Links

• Robert Israel, Table of n, a(n) for n = 1..10011

Crossrefs

Cf. A056108.

Programs

Maple

seq(op([seq(2*n+2*k,k=0..n-2),1]),n=1..10); # Robert Israel, Jan 15 2016

Mathematica

Flatten[Table[Join[{1},Range[n,2n-3,2]],{n,4,30,2}]] (* Harvey P. Dale, Nov 06 2013 *)

Formula

G.f.: 2*x/(1-x)^2 - 2*(2-x)/(1-x)*Sum_{n>=1} n*x^(n*(n+1)/2) + (3-x)/(1-x)*Sum_{n>=1} x^(n*(n+1)/2). - Robert Israel, Jan 15 2016