This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A291213 Start from the singleton set S = {n}, and unless 1 is already a member of S, generate on each iteration a new set where each odd number k is replaced by 3k+1, and each even number k is replaced by 3k+1 and k/2. a(n) is the total size of the set from the singleton through after the first iteration which has produced 1 as a member, inclusive. 1
 1, 3, 36, 6, 20, 72, 1168, 11, 216, 35, 576, 143, 111, 2422, 1657, 19, 336, 378, 6253, 66, 51, 1167, 820, 241, 24096, 180, 18805, 215, 3833, 3488, 368905, 31, 3460, 575, 426, 716, 576, 12387, 57556, 110, 10513, 83, 8948, 2303, 1782, 1656, 175195, 387, 1647 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS See comments at A290100. A290100(n) is the size of the set at the last iteration, while this sequence is the sum of sizes of all generations including the last iteration. A290100(n)/A291213(n) < 29/90 for n = {6, 67, 81, 92, 102, 153, 155, 165, 198, 201, 202, 204, 205, 217, 228, 235, 264, 265, 289, 299, 308, 309, 349, 353, 360, 396, 408, 434, ...}, with n = 6 the greatest observed difference. - Michael De Vlieger, Aug 30 2017 LINKS Michael De Vlieger, Table of n, a(n) for n = 1..450 EXAMPLE For n = 5: Generation   Set 1 (1 term)   5 2 (1 term)   16 3 (2 terms)  8, 49 4 (3 terms)  4, 25, 148 5 (5 terms)  2, 13, 74, 76, 445 6 (8 terms)  1, 7, 37, 38, 40, 223, 229, 1336 thus a(5) = 20 and A290100(5) = 8. MATHEMATICA Table[Length@ Flatten@ NestWhileList[Union@ Flatten[# /. {k_ /; OddQ@ k :> 3 k + 1, k_ /; EvenQ@ k :> {k/2, 3 k + 1}}] &, {n}, FreeQ[#, 1] &], {n, 49}] CROSSREFS Cf. A006577, A127885, A127886, A290100. Sequence in context: A119526 A112404 A189216 * A158301 A105758 A214852 Adjacent sequences:  A291210 A291211 A291212 * A291214 A291215 A291216 KEYWORD nonn AUTHOR Michael De Vlieger, Aug 26 2017 STATUS approved

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

Last modified August 25 21:00 EDT 2019. Contains 326324 sequences. (Running on oeis4.)