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A113158
Primes such that the sum of the predecessor and successor primes is divisible by 43.
15
521, 821, 859, 1069, 1459, 1549, 2203, 2411, 2539, 2837, 2969, 3011, 3089, 3359, 3613, 3823, 4259, 4339, 4561, 4643, 4783, 5503, 5557, 6067, 6619, 6967, 7481, 7699, 7741, 8263, 8779, 9419, 10103, 12041, 12379, 12641, 12899, 13417, 13721, 13759
OFFSET
1,1
COMMENTS
A112681 is mod 3 analogy. A112794 is mod 5 analogy. A112731 is mod 7 analogy. A112789 is mod 11 analogy. A112795 is mod 13 analogy. A112796 is mod 17 analogy. A112804 is mod 19 analogy. A112847 is mod 23 analogy. A112859 is mod 29 analogy.
FORMULA
a(n) = prime(i) is in this sequence iff prime(i-1)+prime(i+1) = 0 mod 43. a(n) = A000040(i) is in this sequence iff A000040(i-1)+A000040(i+1) = 0 mod 43.
EXAMPLE
a(1) = 521 since prevprime(521) + nextprime(521) = 509 + 523 = 1032 = 43 * 24.
a(2) = 821 since prevprime(821) + nextprime(821) = 811 + 823 = 1634 = 43 * 38.
a(3) = 859 since prevprime(859) + nextprime(859) = 857 + 863 = 1720 = 43 * 40.
a(4) = 1069 since prevprime(1069)+nextprime(1069) = 1063+1087 = 2150 = 43 * 50.
MATHEMATICA
Prime@Select[Range[2, 1657], Mod[Prime[ # - 1] + Prime[ # + 1], 43] == 0 &] (* Robert G. Wilson v *)
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, Jan 05 2006
EXTENSIONS
More terms from Robert G. Wilson v, Jan 11 2006
STATUS
approved