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Repeatedly divide by k, add d: k=2, d=5 case.
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%I #5 Sep 11 2018 17:04:10

%S 74,37,42,21,26,13,18,9,14,7,12,6,11

%N Repeatedly divide by k, add d: k=2, d=5 case.

%C The next terms are non-integer: 11/2,21/2,21/4,41/4,41/8,81/8,81/16,161/16,... Independently on the initial term, the terms get closer and closer to the limit cycle a(n) = d*k/(k-1), a(n+1) = a(n)/2, a(n+2) = a(n+1)+d = a(n); in this case 10,5,10. Inspired by A112876.

%F From _Chai Wah Wu_, Sep 11 2018: (Start)

%F a(n) = (3*a(n-2) - a(n-4))/2 for n > 4.

%F G.f.: -x*(x + 2)*(69*x^2 - 74)/(x^4 - 3*x^2 + 2). (End)

%Y Cf. A112876.

%K nonn

%O 1,1

%A _Zak Seidov_, Feb 22 2006