OFFSET
0,1
COMMENTS
In general (except possibly when it begins with 2), the sum of an even number of consecutive primes is even - hence the restriction to odd chain lengths.
LINKS
T. D. Noe, Table of n, a(n) for n = 0..10000
EXAMPLE
17 is the first prime in the chain 17, 19, 23, 29, 31, 37, 41, which is the earliest chain of 2 * 3 + 1 = 7 consecutive primes whose sum, 197, is prime. Hence a(3) = 17.
MATHEMATICA
With[{prs=Prime[Range[1000]]}, First[#]&/@Flatten[Table[Select[ Partition[ prs, 2n+1, 1], PrimeQ[Total[#]]&, 1], {n, 0, 80}], 1]] (* Harvey P. Dale, Jun 21 2013 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Joseph L. Pe, Jan 09 2004
STATUS
approved