|
Search: id:A112794
|
|
|
| A112794 |
|
Primes such that the sum of the predecessor and successor primes is divisible by 5. |
|
+0
15
|
|
| 5, 11, 19, 41, 71, 73, 89, 97, 101, 109, 137, 149, 181, 229, 241, 281, 293, 311, 349, 359, 389, 397, 409, 419, 421, 433, 449, 457, 461, 487, 541, 557, 587, 631, 701, 709, 743, 751, 787, 811, 859, 881, 887, 919, 937, 991, 997, 1009, 1021, 1033, 1049, 1051, 1063
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
FORMULA
|
a(n) = prime(i) is in this sequence iff prime(i-1)+prime(i+1) = 0 mod 5. a(n) = A000040(i) is in this sequence iff A000040(i-1)+A000040(i+1) = 0 mod 5.
|
|
EXAMPLE
|
a(1) = 5 because prevprime(5) + nextprime(5) = 3 + 7 = 10 = 5 * 2.
a(2) = 11 because prevprime(11) + nextprime(11) = 7 + 13 = 20 = 5 * 4.
a(3) = 19 because prevprime(19) + nextprime(19) = 17 + 23 = 40 = 5 * 8.
a(4) = 41 because prevprime(41) + nextprime(41) = 37 + 43 = 80 = 5 * 16.
|
|
MATHEMATICA
|
Prime@ Select[Range[2, 179], Mod[Prime[ # - 1] + Prime[ # + 1], 5] == 0 &] (* Robert G. Wilson v *)
|
|
CROSSREFS
|
Cf. A000040, A112681, A112731, A112789, A112795, A112796, A112804, A112847, A112859, A113155, A113156, A113157, A113158.
Adjacent sequences: A112791 A112792 A112793 this_sequence A112795 A112796 A112797
Sequence in context: A062718 A105914 A106016 this_sequence A072743 A045452 A128927
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
Jonathan Vos Post (jvospost2(AT)yahoo.com), Jan 01 2006
|
|
EXTENSIONS
|
Corrected and extended by Robert G. Wilson v (rgwv(at)rgwv.com), Jan 05 2006
|
|
|
Search completed in 0.002 seconds
|
