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 A185453 Trajectory of 1 under repeated application of the map in A185452. 3
 1, 3, 8, 4, 2, 1, 3, 8, 4, 2, 1, 3, 8, 4, 2, 1, 3, 8, 4, 2, 1, 3, 8, 4, 2, 1, 3, 8, 4, 2, 1, 3, 8, 4, 2, 1, 3, 8, 4, 2, 1, 3, 8, 4, 2, 1, 3, 8, 4, 2, 1, 3, 8, 4, 2, 1, 3, 8, 4, 2, 1, 3, 8, 4, 2, 1, 3, 8, 4, 2, 1, 3, 8, 4, 2, 1, 3, 8, 4, 2, 1, 3, 8, 4, 2, 1, 3, 8, 4, 2, 1, 3, 8, 4, 2, 1, 3, 8, 4, 2, 1, 3, 8, 4, 2, 1, 3, 8, 4 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Periodic with period length 5. REFERENCES J. C. Lagarias, ed., The Ultimate Challenge: The 3x+1 Problem, Amer. Math. Soc., 2010; see page 88. LINKS Index to sequences with linear recurrences with constant coefficients, signature (0,0,0,0,1). FORMULA a(n)=(1/25)*{14*[(n-1) mod 5]+19*(n mod 5)+29*[(n+1) mod 5]-16*[(n+2) mod 5]-[(n+3) mod 5]}, Paolo P. Lava, Mar 10 2011 G.f. -x*(1+3*x+8*x^2+4*x^3+2*x^4) / ( (x-1)*(x^4+x^3+x^2+x+1) ). - R. J. Mathar, Mar 11 2011 MAPLE f:=n->if n mod 2 = 0 then n/2 else (5*n+1)/2; fi; T:=proc(n, M) global f; local t1, i; t1:=[n]; for i from 1 to M-1 do t1:=[op(t1), f(t1[nops(t1)])]; od: t1; end; T(1, 120); MATHEMATICA NestList[If[EvenQ[#], #/2, (5#+1)/2]&, 1, 110] (* From Harvey P. Dale, June 24 2011 *) CROSSREFS Cf. A185452, A185454, A185455. Sequence in context: A002017 A118582 A086179 * A021967 A093524 A200343 Adjacent sequences:  A185450 A185451 A185452 * A185454 A185455 A185456 KEYWORD nonn AUTHOR N. J. A. Sloane, Feb 04 2011 STATUS approved

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