Number of coins needed to make change Relatable scenario: I'm going to the store to buy a single item, but only have a $100k bill. As a result, I need exactly $99,979 in change, and in the fewest coins/bills possible because I'm quite obviously a very practical person.
The denominations of these coins/bills follow the hyperinflation sequence: \$1, 2, 5, 10, 20, 50, 100, 200\$, and so on.
(I'd proposed an OEIS sequence for this, but the first 100k terms are identical to another one so it got rejected)
Task:
Given an amount of money as a nonnegative integer, such as \$73\$, return the minimum number of coins/bills needed to total to that amount. In this example, it would be \$4\$. The coins required would be \$50 + 20 + 2 + 1\$.
As per the standard rules for sequence, you can also choose to return all terms up to an inputted index, or return a (potentially infinite) lazy list or generator that represents the whole sequence.
Test cases:
0       0
1       1
2       1
3       2
4       2
5       1
6       2
7       2
8       3
9       3
10      1
11      2
20      1
30      2
37      4
90      3
111     3
147     5
1000    1
1002    2
1010    2
12478   9

Other:
This is code-golf, so shortest answer in bytes per language wins!
JavaScript (ES7),  36  35 bytes
Similar to other answers. Using a Black Magic formula instead of a lookup table.

f=n=&gt;n&amp;&amp;(n%10)**29%3571%4+f(n/10|0)

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Here is a script that looks for \$(p,m)\$ pairs such that \$(n^p\bmod m)\bmod 4=a_n\$ for all \$n\in[0..9]\$.
It's worth noting that this code takes IEEE-754 precision errors into account. So the results are correct but the math is wrong.
With exact values, we could do instead:
$$\big((n \bmod 10)^{18}\bmod 4011\big)\bmod 4$$
Or better yet, as suggested by @dingledooper:
$$\big((n \bmod 10)^{55}\bmod 767\big)\bmod 4$$
For instance, in Python:
Python 2, 40 bytes

f=lambda n:n and(n%10)**55%767%4+f(n/10)

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JavaScript (ES7), 71 bytes
Expects the amount as a string.
A naive recursive approach that subtracts one coin/bill at a time.

n=&gt;(k=10**n.length,g=t=&gt;+n?k&gt;n?g(t,k/=~++i%3?2:2.5):g(t+1,n-=k):t)(i=0)

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