The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A133419 Image of n under one application of the "5x+1" map. 10
 6, 1, 1, 2, 26, 3, 36, 4, 3, 5, 56, 6, 66, 7, 5, 8, 86, 9, 96, 10, 7, 11, 116, 12, 126, 13, 9, 14, 146, 15, 156, 16, 11, 17, 176, 18, 186, 19, 13, 20, 206, 21, 216, 22, 15, 23, 236, 24, 246, 25, 17, 26, 266, 27, 276, 28, 19, 29, 296, 30, 306, 31, 21, 32, 326, 33, 336, 34, 23, 35 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The 5x+1 map sends x to x/2 if x is even, x/3 if x is odd and divisible by 3, otherwise 5x+1. LINKS Table of n, a(n) for n=1..70. Tomás Oliveira e Silva, The px+1 problem Index entries for sequences related to 3x+1 (or Collatz) problem FORMULA From Chai Wah Wu, Mar 04 2018: (Start) a(n) = 2*a(n-6) - a(n-12) for n > 12. G.f.: x*(4*x^10 + x^9 + x^8 + 2*x^7 + 24*x^6 + 3*x^5 + 26*x^4 + 2*x^3 + x^2 + x + 6)/(x^12 - 2*x^6 + 1). (End) MATHEMATICA Table[If[EvenQ[n], n/2, If[Mod[n, 3] == 0, n/3, 5*n + 1]], {n, 1, 80}] (* Stefan Steinerberger, Feb 16 2008 *) Table[Which[EvenQ[n], n/2, Divisible[n, 3], n/3, True, 5n+1], {n, 70}] (* Harvey P. Dale, Jul 08 2018 *) PROG (PARI) a(n)=if(n%2, if(n%3, 5*n+1, n/3), n/2) \\ Charles R Greathouse IV, Sep 02 2015 CROSSREFS Cf. A133420. Sequence in context: A364129 A336179 A350034 * A010134 A019713 A155824 Adjacent sequences: A133416 A133417 A133418 * A133420 A133421 A133422 KEYWORD nonn,easy AUTHOR N. J. A. Sloane, Nov 27 2007 EXTENSIONS More terms from Stefan Steinerberger, Feb 16 2008 Comment clarified by Chai Wah Wu, Mar 04 2018 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified March 2 04:55 EST 2024. Contains 370460 sequences. (Running on oeis4.)