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A123390 Triangle read by rows: n-th row starts with n and continues with half the previous value as long as that is even. 2
1, 2, 1, 3, 4, 2, 1, 5, 6, 3, 7, 8, 4, 2, 1, 9, 10, 5, 11, 12, 6, 3, 13, 14, 7, 15, 16, 8, 4, 2, 1, 17, 18, 9, 19, 20, 10, 5, 21, 22, 11, 23, 24, 12, 6, 3, 25, 26, 13, 27, 28, 14, 7, 29, 30, 15, 31, 32, 16, 8, 4, 2, 1, 33, 34, 17, 35, 36, 18, 9, 37, 38, 19, 39, 40, 20, 10, 5, 41, 42, 21 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

A fractal sequence, generated by the rule a(n) is a new maximum when a(n-1) is odd and a repetition of an earlier value when a(n-1) is even.

LINKS

Alois P. Heinz, Rows n = 1..10000, flattened

FORMULA

a(1) = 1, for n > 1, if a(n-1) is even, a(n) = a(n-1)/2, otherwise a(n) = (max_{k<n} a(k)) + 1.

Ordinal transform of A082850.

EXAMPLE

Triangle starts

1;

2, 1;

3;

4, 2, 1;

5;

6, 3;

7;

8, 4, 2, 1;

9;

10, 5;

11;

12, 6, 3;

13;

MAPLE

T:= proc(n) local m, l; m:=n; l:= m;

      while irem(m, 2, 'm')=0 do l:=l, m od: l

    end:

seq(T(n), n=1..40);  # Alois P. Heinz, Oct 09 2015

MATHEMATICA

Flatten[Function[n, NestWhile[Append[#, Last[#]/2] &, {n}, EvenQ[Last[#]] &]][#] & /@ Range[20]] (* Birkas Gyorgy, Apr 13 2011 *)

CROSSREFS

Row lengths are A001511. Cf. A120385.

Sequence in context: A273823 A112384 A248514 * A306806 A306805 A162598

Adjacent sequences:  A123387 A123388 A123389 * A123391 A123392 A123393

KEYWORD

nonn,tabf

AUTHOR

Franklin T. Adams-Watters, Oct 13 2006

STATUS

approved

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Last modified April 23 12:15 EDT 2021. Contains 343204 sequences. (Running on oeis4.)