A118627 - OEIS

The OEIS is supported by the many generous donors to the OEIS Foundation.

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give

A118627

a(1) = a(2) = 1. For n >=3, a(n) = the a(n-2)th integer, among those positive integers which are missing from the first (m-1) terms of the sequence, below a(n-1) if such a positive integer exists. Otherwise, a(n) = the a(n-2)th integer, among those positive integers which are missing from the first (m-1) terms of the sequence, above a(n-1).

1, 1, 2, 3, 5, 8, 13, 21, 6, 30, 24, 55, 31, 87, 56, 144, 88, 233, 145, 379, 234, 614, 380, 995, 615, 1611, 996, 2608, 1612, 4221, 2609, 6831, 4222, 11054, 6832, 17887, 11055, 28943, 17888, 46832, 28944, 75777, 46833, 122611, 75778, 198390, 122612, 321003

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

OFFSET

1,3

LINKS

Table of n, a(n) for n=1..48.

EXAMPLE

The first 8 terms of the sequence are 1,1,2,3,5,8,13,21. Those integers which are missing from the first 8 terms of the sequence form the sequence 4,6,7,9,10,11,12,14,15,16,17,18,19,20,.. Counting down from a(8)=21 a total of a(7)=13 positions in this sequence of missing terms, we land on 6. So a(9) = 6.

There are fewer than a(8)=21 missing positive integers below a(9)=6, so we count UP to get a(10). a(10) is what we land on when counting up from 6 a total of a(8)=21 positions, skipping over terms which occur earlier in the sequence. So a(10) = 30.

CROSSREFS

Sequence in context: A137290 A268962 A121104 * A358404 A080787 A065124

Adjacent sequences: A118624 A118625 A118626 * A118628 A118629 A118630

KEYWORD

easy,nonn

AUTHOR

Leroy Quet, May 09 2006

EXTENSIONS

More terms from Joshua Zucker, Jul 27 2006

STATUS

approved