OFFSET
1,1
COMMENTS
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
FORMULA
EXAMPLE
a(1) = 311 since prevprime(311) + nextprime(311) = 307 + 313 = 620 = 31 * 20.
a(2) = 401 since prevprime(401) + nextprime(401) = 397 + 409 = 806 = 31 * 26.
a(3) = 863 since prevprime(863) + nextprime(863) = 859 + 877 = 1736 = 31 * 56.
a(4) = 907 since prevprime(907) + nextprime(907) = 887 + 911 = 1798 = 31 * 58.
MATHEMATICA
Prime@Select[Range[2, 1531], Mod[Prime[ # - 1] + Prime[ # + 1], 31] == 0 &] (* Robert G. Wilson v *)
Transpose[Select[Partition[Prime[Range[1500]], 3, 1], Divisible[#[[1]]+#[[3]], 31]&]][[2]] (* Harvey P. Dale, Mar 23 2012 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, Jan 05 2006
EXTENSIONS
Corrected and extended by Robert G. Wilson v, Jan 11 2006
STATUS
approved