0,2

A000041 begins 1 1 2 3 5 7 11 15 22 30 42 ... and when shifted 0 0 1 1 2 3 5 7 11 15 22 ... by subtraction yielding 1 1 1 2 3 4 6 8 11 15 20 ... shape seq A027736.

Table of n, a(n) for n=0..36.

The original tree begins

1

2

3 4

5 6 8

7 10 9 12 16

11 14 15 20 18 24 32

multiplying by four yields

4

8

12 16

20 24 32

etc.

These are the values to be omitted leaving

3

5 6

7 10 9

11 14 15 18

Cf. A000041 A027336 A129129.

Sequence in context: A100693 A030159 A030161 * A259444 A071591 A089105

Adjacent sequences: A129122 A129123 A129124 * A129126 A129127 A129128

easy,more,nonn,tabf

Alford Arnold, Apr 04 2007

approved