A134825 Floor of the even-indexed Bernoulli numbers B_{2n} = A000367(n)/A002445(n).

1, 0, -1, 0, -1, 0, -1, 1, -8, 54, -530, 6192, -86581, 1425517, -27298232, 601580873, -15116315768, 429614643061, -13711655205089, 488332318973593, -19296579341940069, 841693047573682615, -40338071854059455414, 2115074863808199160560, -120866265222965259346028

Offset: 0

Author

Wolfdieter Lang, Nov 13 2007

Keywords

• sign
• easy

Examples

			n=4: B_8=-1/30=-0,033... hence a(4)=-1.
		

References

• C. J. Moreno and S. S. Wagstaff, Jr., Sums of Squares of Integers, Chapman & Hall, 2006, p. 107.

Crossrefs

Cf. A000367, A002445, A014509, A027641, A027642.

Programs

Mathematica

Floor@BernoulliB[2 Range[0, 20]] (* Vladimir Reshetnikov, Nov 12 2015 *)

PARI

vector(30, n, n--; floor(bernfrac(2*n))) \\ Altug Alkan, Nov 12 2015

Formula

a(n) = floor(B_(2n)), n>=0, with B_{2n} = A000367(n)/A002445(n) = A027641(2n)/A027642(2n).