%I A096102
%S A096102 1,3,7,9,21,13
%N 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.
%C A096102 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.
%C A096102 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
%e A096102 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.
%Y A096102 Cf. A096100, A096101.
%Y A096102 Sequence in context: A073573 A059621 A034926 this_sequence A045797 A118555 
               A056652
%Y A096102 Adjacent sequences: A096099 A096100 A096101 this_sequence A096103 A096104 
               A096105
%K A096102 nonn
%O A096102 1,2
%A A096102 Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Jun 24 2004
%E A096102 Edited and corrected by Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), 
               Jun 29 2004