%I A117809
%S A117809 2,7,3,26,13,7,96,48,24,12,362,181,91,46,23,1350,675,337,168,84,42,5042,
%T A117809 2521,1261,631,316,158,79,18816,9408,4704,2352,1176,588,294,147,70226,
               35113,
%U A117809 17557,8779,4390,2195,1098,549,275,262086,131043,65521,32760,16380,8190,
               4095
%V A117809 -2,7,3,-26,-13,-7,96,48,24,12,-362,-181,-91,-46,-23,1350,675,337,168,
               84,42,-5042,
%W A117809 -2521,-1261,-631,-316,-158,-79,18816,9408,4704,2352,1176,588,294,147,
               -70226,-35113,
%X A117809 -17557,-8779,-4390,-2195,-1098,-549,-275,262086,131043,65521,32760,16380,
               8190,4095
%N A117809 a(n,m) =Floor[N[(-2 + Sqrt[3])^n + (-2 - Sqrt[3])^n]/2^m].
%C A117809 A triangular prime alternating sign Binet like function.
%e A117809 -2
%e A117809 7, 3
%e A117809 -26, -13,-7
%e A117809 96, 48, 24, 12
%e A117809 -362,-181, -91, -46, -23
%e A117809 1350, 675, 337, 168, 84, 42
%t A117809 f[n_, m_] = N[(-2 + Sqrt[3])^n + (-2 - Sqrt[3])^n]/2^m a = Table[Table[Floor[f[n, 
               m]], {m, 1, n}], {n, 1, 10}] aa = Flatten[a] pp = Flatten[Table[If[PrimeQ[aa[[n]]], 
               aa[[n]], {}], {n, 1, Length[aa]}]] Length[pp]/Length[aa]
%Y A117809 Sequence in context: A138751 A112303 A089124 this_sequence A052091 A090276 
               A090564
%Y A117809 Adjacent sequences: A117806 A117807 A117808 this_sequence A117810 A117811 
               A117812
%K A117809 sign,tabl
%O A117809 0,1
%A A117809 Roger L. Bagula (rlbagulatftn(AT)yahoo.com), Apr 29 2006