This site is supported by donations to The OEIS Foundation. Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A096102 a(1) = 1, a(2) = 3; for n > 2: a(n) = smallest (odd) number not occurring earlier such that the sum of each section of odd length >=3 is prime. 0
 1, 3, 7, 9, 21, 13 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS If 1, 3, 7, 13 are taken (rather arbitrarily) as starting terms, then the continuation is 17, 31, 11, 25, 5, 37, 341, 163, 647, 571, 989, 3451, 17669, 206413, 6767, 252289, but no number < 10000000 is suited to continue this sequence further. There are no further terms. For k to qualify as next term the sums 21+13+k, 7+9+21+13+k and 1+3+7+9+21+13+k have to be prime. One of these sums however is divisible by 3, since 34+k = k+1 (mod 3), 50+k = k+2 (mod 3) and 54+k = k (mod 3). - Klaus Brockhaus, Jul 02 2004 LINKS EXAMPLE 1+3+7 = 11, 3+7+9 = 19, 7+9+21 = 37, 9+21+13 = 43, 1+3+7+9+21 = 41, 3+7+9+21+13 = 53 are all prime. CROSSREFS Cf. A096100, A096101. Sequence in context: A304128 A304539 A306124 * A316157 A045797 A118555 Adjacent sequences:  A096099 A096100 A096101 * A096103 A096104 A096105 KEYWORD nonn AUTHOR Amarnath Murthy, Jun 24 2004 EXTENSIONS Edited and corrected by Klaus Brockhaus, Jun 29 2004 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 October 13 18:57 EDT 2019. Contains 327981 sequences. (Running on oeis4.)