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

0,2

Links

Table of n, a(n) for n=0..39.

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

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.

Example

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

Crossrefs

Cf. A056109, A049450, A204028.

Sequence in context: A100899 A099540 A190695 * A180739 A274679 A229218

Adjacent sequences: A238374 A238375 A238376 * A238378 A238379 A238380

Keyword

easy,nonn

Author

Philippe Deléham, Feb 25 2014

Extensions

Corrected by R. J. Mathar, Aug 08 2015

Status

approved