A126945 The sequence a[n]+b[n]+c[n]+d[n] defined in A126940.

1, 5, 15, 47, 151, 479, 1519, 4827, 15333, 48693, 154651, 491189, 1560039, 4954755, 15736581, 49980243, 158739915, 504166505, 1601260009, 5085687979, 16152418715, 51300951395, 162934583329, 517489007515, 1643572944909, 5220076149055, 16579242853235

Offset

0,2

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..1992

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

Formula

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

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*[1; 5; 15; 47; 151; 479])[1, 1] \\ Charles R Greathouse IV, May 29 2026

Crossrefs

Cf. A126940.

Sequence in context: A184262 A126944 A077841 * A191641 A199892 A152809

Adjacent sequences: A126942 A126943 A126944 * A126946 A126947 A126948

Keyword

nonn,easy

Author

N. J. A. Sloane, Mar 18 2007

Status

approved