A122439 Expansion of 1/(1-2x-x^2+4x^4).

1, 2, 5, 12, 25, 54, 113, 232, 477, 970, 1965, 3972, 8001, 16094, 32329, 64864, 130053, 260594, 521925, 1044988, 2091689, 4185990, 8375969, 16757976, 33525165, 67064346, 134149981, 268332404, 536714129, 1073503278, 2147120761

Offset: 0

Author

Paul Barry, Sep 05 2006

Keywords

• easy
• nonn

Comments

Diagonal sums of number triangle A122438. Convolution of A052947 and 2^n.

Links

• Index entries for linear recurrences with constant coefficients, signature (2,1,0,-4).

Programs

Mathematica

CoefficientList[Series[1/(1 - 2x - x^2 + 4x^4), {x, 0, 31}], x] (* Robert G. Wilson v, Sep 14 2006 *)
LinearRecurrence[{2,1,0,-4},{1,2,5,12},40] (* Harvey P. Dale, Jul 30 2024 *)

Extensions

More terms from Robert G. Wilson v, Sep 14 2006