A238377 Row sums of triangle in A204028.

1, 2, 6, 10, 17, 24, 34, 44, 57, 70, 86, 102, 121, 140, 162, 184, 209, 234, 262, 290, 321, 352, 386, 420, 457, 494, 534, 574, 617, 660, 706, 752, 801, 850, 902, 954, 1009, 1064, 1122, 1180

Offset: 0

Author

Philippe Deléham, Feb 25 2014

Keywords

• easy
• nonn

Examples

			Triangle in A204028 begins:
  1;............................sum = 1
  1, 1;.........................sum = 2
  1, 4, 1;......................sum = 6
  1, 4, 4, 1;...................sum = 10
  1, 4, 7, 4, 1;................sum = 17
  1, 4, 7, 7, 4, 1;.............sum = 24
  1, 4, 7, 10, 7, 4, 1;.........sum = 34
  1, 4, 7, 10, 10, 7, 4, 1;.....sum = 44
		

Links

• Index entries for linear recurrences with constant coefficients, signature (2,0,-2,1).

Crossrefs

Cf. A056109, A049450, A204028.

Formula

G.f.: (1+2*x^2)/((1+x)*(1-x)^3).

a(2*n) = A056109(n).

a(2*n+1) = A049450(n+1) = 2*A000326(n+1).

a(n) = 2*a(n-1) - 2*a(n-3) + a(n-4), a(0) = 1, a(1) = 2, a(2) = 6, a(3) = 10.

Extensions

Corrected by R. J. Mathar, Aug 08 2015