A089607 a(n)=((-1)^(n+1)*A002425(n)) modulo 4.

1, 3, 1, 3, 3, 1, 1, 3, 3, 3, 1, 1, 3, 1, 1, 3, 3, 3, 1, 3, 3, 1, 1, 1, 3, 3, 1, 1, 3, 1, 1, 3, 3, 3, 1, 3, 3, 1, 1, 3, 3, 3, 1, 1, 3, 1, 1, 1, 3, 3, 1, 3, 3, 1, 1, 1, 3, 3, 1, 1, 3, 1, 1, 3, 3, 3, 1, 3, 3, 1, 1, 3, 3, 3, 1, 1, 3, 1, 1, 3, 3, 3, 1, 3, 3, 1, 1, 1, 3, 3, 1, 1, 3, 1, 1, 1, 3, 3, 1, 3, 3, 1, 1, 3, 3

Offset

1,2

Links

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

Formula

a(1)=1; for n>=2, a(n) = 2*A014577(n-1)+1

Prog

(PARI) a(n)=numerator(2/n*(4^n-1)*bernfrac(2*n))%4

Crossrefs

Cf. A056832.

Sequence in context: A122567 A122431 A279340 * A216637 A358643 A234308

Adjacent sequences: A089604 A089605 A089606 * A089608 A089609 A089610

Keyword

nonn

Author

Benoit Cloitre, Dec 30 2003

Status

approved