A174837 Sequence built as it follows in comments.

9, 2, 45, 2, 11, 2, 225, 2, 11, 2, 56, 2, 11, 2, 1125, 2, 11, 2, 56, 2, 11, 281, 2, 11, 2, 56, 2, 11, 2, 5625

Offset: 0

Author

Richard Choulet, Mar 30 2010

Keywords

• easy
• nonn
• uned

Comments

If we denote "A" the finite sequence between a(2^(n-1)-2) and a(2^n-2), the subsequence of a between

a(2^(n)-2) and a(2^(n+1)-2) is given by: " A - a(3*2^(n-1)-2) - A" for every n>=2.

Examples

			a(4)=a(2*3-2)=(9*4-1)/4=11. a(14)=a(2^4-2)==9*5^3=125*9=1125.
Between a(2) and a(6) the subsequence is "2, 11, 2"; then between a(6) and a(14) the subsequence of a is:
"2, 11, 2, a(10)=56, 2, 11, 2".
It seems that this new sequence gives the number of 2 in the sets of 2 of the sequence A174835.
		

Crossrefs

Cf. A174835.

Formula

a(2n+1)=2. a(2^(n+1)-2)=9*5^n. a(3*2^n-2)=(9*5^n-1)/4.