user35335: Is there a library to know the number of bitcoin mined at a given block number ? 

user60443: There is a fixed rate for how many bitcoins are mined each block. The block reward halves every 210,000 blocks, see Controlled Supply.
Here is a short term bitcoin distribution projection from the Bitcoin Wiki:

To calculate the total coins for a given block, try:
coins.py
block = 210000 * 10
totalCoins = 0

subsidy = 50.0
for i in range(1,block):
    if(i%210000 == 0):
        subsidy = subsidy / 2
    totalCoins += subsidy
    #print i, subsidy, totalCoins

print totalCoins

Also, you might find this helpful: Deflation Calculator

35335: <p>Is there a library to know the number of bitcoin mined at a given block number ? </p>
 60443: <p>There is a fixed rate for how many bitcoins are mined each block. The block reward halves every 210,000 blocks, see <a href="https://en.bitcoin.it/wiki/Controlled_supply" rel="nofollow noreferrer">Controlled Supply</a>.</p>

<p>Here is a short term bitcoin distribution projection from the <a href="https://i.stack.imgur.com/UnN8S.png" rel="nofollow noreferrer">Bitcoin Wiki</a>:</p>

<p><a href="https://i.stack.imgur.com/UnN8S.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/UnN8S.png" alt="enter image description here"></a></p>

<p>To calculate the total coins for a given block, try:</p>

<p><code>coins.py</code></p>

<pre><code>block = 210000 * 10
totalCoins = 0

subsidy = 50.0
for i in range(1,block):
    if(i%210000 == 0):
        subsidy = subsidy / 2
    totalCoins += subsidy
    #print i, subsidy, totalCoins

print totalCoins
</code></pre>

<p>Also, you might find this helpful: <a href="https://github.com/JBaczuk/altcoin_deflation_calculator/blob/master/plot.py" rel="nofollow noreferrer">Deflation Calculator</a></p>
