The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A129141 a(1)=a(2)=1. a(n) = the n-th integer from among those positive integers coprime to (a(n-1)*a(n-2)). 1
 1, 1, 3, 5, 8, 13, 15, 16, 31, 19, 11, 13, 15, 29, 28, 39, 61, 29, 19, 21, 40, 97, 57, 37, 41, 26, 59, 61, 29, 31, 33, 53, 56, 81, 121, 59, 40, 97, 99, 65, 92, 119, 111, 86, 139, 93, 73, 76, 105, 227, 109, 52, 115, 151, 72, 169, 185, 81, 113, 89, 61, 63, 110, 307, 177, 100 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS EXAMPLE a(4)*a(5) = 40. So a(6) = the sixth integer from among those positive integers coprime to 40 (ie, the sixth integer in the sequence 1,3,7,9,11,13,17,19,21,23,...). So a(6) = 13. MAPLE a[1]:=1: a[2]:=1: for n from 3 to 80 do A:={}: for i from 1 to 500 do if gcd(i, a[n-1]*a[n-2])=1 then A:=A union {i} else fi od: a[n]:=A[n]: od: seq(a[n], n=1..80); # Emeric Deutsch, Apr 12 2007 CROSSREFS Cf. A129140. Sequence in context: A020643 A131354 A092360 * A289013 A331467 A337289 Adjacent sequences:  A129138 A129139 A129140 * A129142 A129143 A129144 KEYWORD nonn AUTHOR Leroy Quet, Mar 30 2007 EXTENSIONS More terms from Emeric Deutsch, Apr 12 2007 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
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified September 27 20:35 EDT 2020. Contains 337388 sequences. (Running on oeis4.)