A084518 Partial sums of A084519. Positions of ones in the first differences of A084516.

1, 2, 5, 18, 65, 238, 877, 3234, 11929, 44006, 162341, 598890, 2209361, 8150542, 30068125, 110924178, 409209865, 1509614198, 5569110677, 20544980154, 75792390209, 279605352286, 1031490797581, 3805267877730, 14037995932921

Offset

1,2

Links

Table of n, a(n) for n=1..25.

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

Formula

Empirical G.f.: x*(1-2*x-2*x^2)/((1-x)*(1-3*x-2*x^2-2*x^3)). - Colin Barker, Apr 17 2012

Mathematica

Accumulate[LinearRecurrence[{3, 2, 2}, {1, 1, 3}, 30]] (* Harvey P. Dale, Jul 20 2013 *)

Prog

(PARI) a(n)=([0, 1, 0, 0; 0, 0, 1, 0; 0, 0, 0, 1; -2, 0, -1, 4]^(n-1)*[1; 2; 5; 18])[1, 1] \\ Charles R Greathouse IV, May 29 2026

Crossrefs

Cf. A084519, A084516.

Sequence in context: A354420 A024025 A360185 * A150014 A150015 A150016

Adjacent sequences: A084515 A084516 A084517 * A084519 A084520 A084521

Keyword

nonn,easy

Author

Antti Karttunen, Jun 02 2003

Status

approved