A090399 Expansion of 1/(1-2x+2x^4).

1, 2, 4, 8, 14, 24, 40, 64, 100, 152, 224, 320, 440, 576, 704, 768, 656, 160, -1088, -3712, -8736, -17792, -33408, -59392, -101312, -167040, -267264, -415744, -628864, -923648, -1312768, -1794048, -2330368, -2813440, -3001344, -2414592, -168448, 5289984, 16582656

Offset

0,2

Links

Harvey P. Dale, Table of n, a(n) for n = 0..1000

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

Formula

a(n)=2a(n-1)-2a(n-4); a(n)=sum{k=0..floor(n/3), comb(n-3k, k)2^(n-3k) }.

Mathematica

CoefficientList[Series[1/(1-2x+2x^4), {x, 0, 40}], x] (* or *) LinearRecurrence[ {2, 0, 0, -2}, {1, 2, 4, 8}, 40] (* Harvey P. Dale, Dec 24 2016 *)

Crossrefs

Sequence in context: A053802 A091779 A365666 * A069251 A261988 A128770

Adjacent sequences: A090396 A090397 A090398 * A090400 A090401 A090402

Keyword

easy,sign

Author

Paul Barry, Nov 28 2003

Status

approved