A074381 (p-1)/2 mod 2, where p is the n-th prime for which p+2 is also prime; i.e., a(n)=0 if p==1 (mod 4), a(n)=1 if p==3 (mod 4).

1, 0, 1, 0, 0, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 0, 1, 1, 1, 0, 1, 1, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 1, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 0, 1

Offset

1,1

Links

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

Mathematica

Mod[(Select[Prime/@Range[600], PrimeQ[ #+2]&]-1)/2, 2]

Crossrefs

Cf. A001359, A071695, A071698.

Sequence in context: A266282 A228747 A285162 * A179560 A341602 A128407

Adjacent sequences: A074378 A074379 A074380 * A074382 A074383 A074384

Keyword

nonn,easy

Author

Roger L. Bagula, Sep 24 2002

Extensions

Edited by Dean Hickerson and Robert G. Wilson v, Oct 09 2002

Status

approved