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7*x - 1 Collatz-type sequence starting with a(0) = 11.
1

%I #23 Sep 12 2017 02:50:54

%S 11,76,38,19,132,66,33,230,115,804,402,201,1406,703,4920,2460,1230,

%T 615,4304,2152,1076,538,269,1882,941,6586,3293,23050,11525,80674,

%U 40337,282358,141179,988252,494126,247063,1729440,864720,432360,216180,108090,54045,378314,189157,1324098

%N 7*x - 1 Collatz-type sequence starting with a(0) = 11.

%F a(0) = 11; a(n) = 7*a(n - 1) - 1 if a(n - 1) is odd, a(n) = a(n - 1)/2 if a(n - 1) is even.

%e 11 is odd, so it's followed by 7*11 - 1 = 76.

%e 76 is even, so it's followed by 76/2 = 38.

%t NestList[If[OddQ[#], 7# - 1, #/2] &, 11, 50]

%Y Cf. A063871.

%K nonn,easy

%O 0,1

%A _Alonso del Arte_, Sep 01 2017