A269026 - OEIS

A269026

a(1)=1; for n>1, define a sequence {b(m), m >= 1} by b(1)=a(n-1), b(2)=n, and b(m) = A020639(b(m-2)) + A006530(b(m-1)); then a(n) is the number of terms in that sequence before the first of the infinite string of 4s.

1, 9, 12, 1, 4, 10, 5, 6, 8, 6, 5, 3, 15, 7, 12, 2, 17, 7, 4, 6, 13, 11, 8, 10, 9, 3, 12, 9, 11, 3, 12, 2, 16, 6, 12, 10, 5, 11, 12, 6, 9, 7, 12, 14, 13, 11, 16, 10, 5, 7, 12, 14, 8, 10, 5, 11, 4, 10, 17, 15, 15, 7, 8, 2, 5, 3, 15, 7, 4, 9, 12, 10, 5, 10, 13, 3, 11, 11, 11

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Michel Marcus, Table of n, a(n) for n = 1..10000

EXAMPLE

n = 3:

a(n-1) = a(2) = 9;

b(1) = 9, b(2) = 3;

the sequence generated is: 9, 3, 6, 6, 5, 7, 12, 10, 7, 9, 10, 8, 4, 4, 4, ...

There are 12 terms before the first of the infinite 4s, so a(3) = 12.

PROG