# [Ruby], <s>40</s> 36 bytes

Python answer port but Ruby strict typing means I can't coerce booleans into integers.

-4 bytes from dingledooper.

<!-- language-all: lang-ruby -->

 f=->n,a{n>0?a.sum{|e|f[n-e,a]}:1<<n}

[Try it online!][TIO-k8x9i4w5]

[Ruby]: https://www.ruby-lang.org/
[TIO-k8x9i4w5]: https://tio.run/##NYtNCoMwFIT3nmIWpYsSQ4wGi6g9SBFJaWwFfQ1VKUU9e/o2XQzz8zHv5fYNoavimoRdqVYXK6dlXDe3dVeKnbDNXiRlSXv4PPvB4eHmKQJI4GRR4dDKyQ/9LEfrcSzmV9sz9eCzgG0iR/dgoJEiixL1D4bNIOegGHLVOU8pyxhkWsGc1Q8 "Ruby – Try It Online"