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

0,1

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.

Links

Table of n, a(n) for n=0..29.

Formula

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

Example

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.

Sequence in context: A152020 A055516 A248314 * A096042 A038292 A294685

Adjacent sequences: A174834 A174835 A174836 * A174838 A174839 A174840

Keyword

easy,nonn,uned

Author

Richard Choulet, Mar 30 2010

Status

approved