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A126945
The sequence a[n]+b[n]+c[n]+d[n] defined in A126940.
2
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
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
CROSSREFS
Sequence in context: A184262 A126944 A077841 * A191641 A199892 A152809
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Mar 18 2007
STATUS
approved