ioannis.c is an entry "Ioannis" submitted to Bignum Bakeoff.[1] The code defines a function similar to the Ackermann function, defines a single-argument function using it, and iterates that function.
The output is approximately equal to \(f_{\omega+1}(115)\), which is larger than Graham's number.
Code
int a(int k,int m,int n)
{if (k==1) return(m+n);
else {if (n==1) return m;
else return a(k-1,m,a(k,m,n-1));}}
#define d(n) a(n,n,n)
int main(void)
{return d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(
d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(
d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(
d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(
d(d(d(d(d(d(d(d(9)))))))))))))))))))))))))))))))))))))))
))))))))))))))))))))))))))))))))))))))))))))))))))))))))
)))))))))))))))))))));}
Sources
See also
Large numbers in computers
Main article: Numbers in computer arithmetic
127 · 128 · 256 · 32767 · 32768 · 65536 · 2147483647 · 4294967296 · 9007199254740991 · 9223372036854775807 · FRACTRAN catalogue numbersBignum Bakeoff contestants: pete-3.c · pete-9.c · pete-8.c · harper.c · ioannis.c · chan-2.c · chan-3.c · pete-4.c · chan.c · pete-5.c · pete-6.c · pete-7.c · marxen.c · loader.c
Channel systems: lossy channel system · priority channel system
Concepts: Recursion