A123635 Residue mod 3 of average of n-th and (n+1)st odd primes.

1, 0, 0, 0, 0, 0, 0, 2, 0, 1, 0, 0, 0, 2, 2, 0, 1, 0, 0, 1, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 1, 1, 0, 2, 2, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 2, 0, 0, 2, 2, 2, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 2, 0, 1, 1, 0, 2, 0, 0, 0, 0, 0, 0, 0, 1, 0, 2, 0, 0, 0, 0, 2, 0, 0, 0, 0, 2, 2, 0, 1, 1, 0, 2, 2, 0, 1, 0

Offset

1,8

Links

Table of n, a(n) for n=1..105.

Formula

a(n) = (p(n)+p(n+1))/2 mod 3, where p(n) = n-th odd prime.

Example

Odd primes: 3,5,7,11,13,17,23,...
Averages: (3+5)/2, (5+7)/2, (7+11)/2, ...
Residues mod 3: 1, 0, 0, 0, 0, 0, 0, 2, ...

Mathematica

f[n_] := Mod[Prime[n + 1] + Prime[n + 2], 6]/2; Array[f, 105}] (* Robert G. Wilson v Oct 07 2006 *)

Crossrefs

Cf. A065091.

Sequence in context: A318875 A187143 A187144 * A124304 A165408 A186733

Adjacent sequences: A123632 A123633 A123634 * A123636 A123637 A123638

Keyword

easy,nonn

Author

Clark Kimberling, Oct 03 2006

Status

approved