Genocchi number

The Genocchi numbers, named after Angelo Genocchi, are a sequence of integers, G_n that satisfy the relation

$\frac{2t}{e^t+1}=\sum_{n=1}^{\infty} G_n\frac{t^n}{n!}$ .

The first few Genocchi numbers are 1, -1, 0, 1, 0, -3, 0, 17 (sequence A001469 in OEIS). G_n is 0 for odd n > 1.

It has been proven that -3 and 17 are the only prime Genocchi numbers.

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