A126948 The sequence d[n] defined in A126940.

0, 0, 4, 12, 34, 110, 354, 1120, 3552, 11290, 35862, 113884, 361702, 1148810, 3648670, 11588338, 36805222, 116895404, 371266018, 1179160836, 3745078428, 11894570660, 37777796510, 119984315496, 381076645196, 1210319938646, 3844041278068, 12208882029838

Offset

0,3

Comments

Linear recurrence and empirical g.f confirmed for more terms. - Ray Chandler, Mar 07 2024

Links

Ray Chandler, Table of n, a(n) for n = 0..1993

Index entries for linear recurrences with constant coefficients, signature (2, 1, 7, 4, 4, 1).

Formula

Empirical g.f.: -2*x^2*(x^3+3*x^2+2*x+2) / (x^6+4*x^5+4*x^4+7*x^3+x^2+2*x-1). - Colin Barker, Apr 08 2013

Mathematica

LinearRecurrence[{2, 1, 7, 4, 4, 1}, {0, 0, 4, 12, 34, 110}, 40] (* Harvey P. Dale, Apr 15 2024 *)

Prog

(PARI) a(n)=([0, 1, 0, 0, 0, 0; 0, 0, 1, 0, 0, 0; 0, 0, 0, 1, 0, 0; 0, 0, 0, 0, 1, 0; 0, 0, 0, 0, 0, 1; 1, 4, 4, 7, 1, 2]^n*[0; 0; 4; 12; 34; 110])[1, 1] \\ Charles R Greathouse IV, May 29 2026

Crossrefs

Cf. A126940.

Sequence in context: A077994 A077843 A061703 * A131593 A119683 A340492

Adjacent sequences: A126945 A126946 A126947 * A126949 A126950 A126951

Keyword

nonn,easy

Author

N. J. A. Sloane, Mar 18 2007

Status

approved