A329983 For any n > 0, define the sequence b(1) = n, b(i+1) = (b(i) * i) mod (b(i) + i); a(n) is the least i such that b(i) = 0, or -1 if 0 is never reached.
1, 13, 3, 85, 13, 85, 7, 58, 4, 13, 7, 85, 5, 7, 13, 58, 58, 85, 85, 13, 5, 85, 7, 291, 13, 85, 58, 85, 58, 7, 85, 291, 85, 85, 13, 58, 13, 58, 291, 11, 6, 58, 13, 7, 13, 85, 7, 291, 58, 85, 9, 85, 7, 13, 13, 58, 85, 13, 9, 58, 291, 291, 13, 11
Offset: 0
Keywords
Links
- Rémy Sigrist, Table of n, a(n) for n = 0..10000
Crossrefs
Cf. A308651.
Programs
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PARI
f(m, n) = (m*n) % (m+n); a(n) = {my(i=1); while (n, n = f(n, i); i++;); i;} \\ Michel Marcus, Nov 28 2019 -
Python
def k(a,b): return ((a*b)%(a+b)) numberList=[] def repeat(a): i=1 while a!=0: a= k(a,i) i=i+1 numberList.append(i) for x in range(10000): repeat(x) print(numberList)