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A214614 Irregular triangle read by rows: row n gives numbers <= n whose Collatz trajectory contains the trajectory of n. 2
1, 1, 2, 1, 2, 3, 1, 2, 4, 1, 2, 4, 5, 1, 2, 3, 4, 5, 6, 1, 2, 4, 5, 7, 1, 2, 4, 8, 1, 2, 4, 5, 7, 8, 9, 1, 2, 4, 5, 8, 10, 1, 2, 4, 5, 8, 10, 11, 1, 2, 3, 4, 5, 6, 8, 10, 12, 1, 2, 4, 5, 8, 10, 13, 1, 2, 4, 5, 7, 8, 10, 11, 13, 14, 1, 2, 4, 5, 8, 10, 15 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Each row has A159999(n) elements and ends in n.

LINKS

T. D. Noe, Rows n = 1..200 of irregular triangle, flattened

Index entries for sequences related to 3x+1 (or Collatz) problem

EXAMPLE

Rows of triangle:

{1},

{1, 2},

{1, 2, 3},

{1, 2, 4},

{1, 2, 4, 5},

{1, 2, 3, 4, 5, 6},

{1, 2, 4, 5, 7},

{1, 2, 4, 8},

{1, 2, 4, 5, 7, 8, 9},

{1, 2, 4, 5, 8, 10}

MATHEMATICA

Collatz[n_] := NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, n, # > 1 &]; f[n_] := Module[{c = Collatz[n]}, Select[c, # <= n &]]; t = Table[f[n], {n, 20}]; Flatten[t] (* T. D. Noe, Mar 07 2013 *)

PROG

(Haskell)

import Data.List (sort)

a214614 n k = a214614_tabf !! (n-1) (k-1)

a214614_row n = a214614_tabf !! (n-1)

a214614_tabf = zipWith f [1..] a070165_tabf where

                       f v ws = sort $ filter (<= v) ws

-- Reinhard Zumkeller, Sep 01 2014

CROSSREFS

Cf. A070165, A159999.

Sequence in context: A126260 A264846 A265691 * A265692 A194976 A195082

Adjacent sequences:  A214611 A214612 A214613 * A214615 A214616 A214617

KEYWORD

nonn,tabf

AUTHOR

Jayanta Basu, Mar 06 2013

STATUS

approved

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Last modified February 22 06:05 EST 2019. Contains 320389 sequences. (Running on oeis4.)