In mathematics, the Bernoulli numbers B_n are a sequence of rational numbers with deep connections to number theory. The values of the first few Bernoulli numbers are

B₀ = 1, B₁ = ±, B₂ = , B₃ = 0, B₄ = -, B₅ = 0, B₆ = , B₇ = 0, B₈ = -.

If the convention B₁ = - is used, this sequence is also known as the first Bernoulli numbers ( / in OEIS); with the convention B₁ = + is known as the second Bernoulli numbers ( / ). Except for this one difference, the first and second Bernoulli numbers agree. Since B_n = 0 for all odd n > 1, and many formulas only involve even-index Bernoulli numbers, some authors write B_n instead of B_2n.