| DATA
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1, 3, 23, 181, 1425, 11219, 88327, 695397, 5474849, 43103395, 339352311, 2671715093, 21034368433, 165603232371, 1303791490535, 10264728691909, 80814038044737, 636247575665987, 5009166567283159, 39437084962599285, 310487513133511121, 2444463020105489683
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| FORMULA
|
G.f.: (1-5*x)/(1-8*x+x^2). [From _). - _Philippe Deléham_, Mar 28 2009]
a(n) = A001090(n+1)-5*A001090(n). [From _). - _R. J. Mathar_, Mar 29 2009]
a(n) = (((4-sqrt(15))^n*(1+sqrt(15))+(-1+sqrt(15))*(4+sqrt(15))^n))/(2*sqrt(15)). - Colin Barker, Oct 12 2015
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