This site is supported by donations to The OEIS Foundation.

 Annual appeal: Please make a donation to keep the OEIS running! Over 6000 articles have referenced us, often saying "we discovered this result with the help of the OEIS". Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A122984 Smallest positive composite number, relatively prime to n, such that a(n)+n is also composite. 2
 8, 25, 22, 21, 4, 49, 8, 25, 16, 39, 4, 65, 8, 25, 34, 9, 4, 77, 6, 49, 4, 27, 4, 25, 8, 9, 8, 27, 4, 91, 4, 25, 16, 15, 4, 49, 8, 25, 10, 9, 4, 143, 6, 21, 4, 9, 4, 77, 6, 27, 4, 25, 4, 65, 8, 9, 8, 27, 4, 143, 4, 15, 22, 21, 4, 25, 8, 9, 8, 51, 4, 49, 4, 21, 16, 9, 4, 55, 6, 39, 4, 9, 4, 85 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Does not include every composite number; in particular, 12 is not present. If a(n) = 12, gcd(n,12) = 1, but then one of n+4 and n+8 is divisible by 3. LINKS CROSSREFS Equals A122985(n) - n. Cf. A096076. Sequence in context: A103954 A217012 A200838 * A254341 A188477 A045860 Adjacent sequences:  A122981 A122982 A122983 * A122985 A122986 A122987 KEYWORD easy,nonn AUTHOR Franklin T. Adams-Watters, Sep 22 2006 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.