[seqfan] Two consecutive integers sum to a prime
franktaw at netscape.net
franktaw at netscape.net
Thu Jan 7 19:22:07 CET 2010
Here's (to me) a more interesting question relating to A055265: which
primes are not represented as the sum of consecutive terms? This
starts:
2, 197, 199, 317, 467, 563, 599, 653, 811, 829, 863, 977, 1019, 1039,
1093, 1097, 1103, 1327, 1373, 1429, 1433, 1607, 1609, 1613, 1669, 1877,
1879
This is based on looking at the first 1000 terms of A055265; to that
point, the largest missing integer was 992, so no prime less than 1984
could still occur. 1993 and 1999 had not yet occurred, but might yet.
I find it intriguing how many of the early primes occur. I was about
ready to conjecture that every odd prime occurs (looking at the first
100 terms of A055265), but decided to look a bit further.
Also note the twin prime occurrences: 197 & 199, 1607 & 1609, 1877 &
1879. That's a lot for so few primes of this size. There does seem to
be some clustering effect: you get a lot of pairs summing to a small
cluster of primes, and then the integers in that range are exhausted
and you get a jump to a higher level.
Franklin T. Adams-Watters
-----Original Message-----
From: Eric Angelini <Eric.Angelini at kntv.be>
...
Based on:
http://www2.research.att.com/~njas/sequences/A055265
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