OFFSET
1,2
COMMENTS
Least integer k such that the number of perfect squares in {k, f(k), f(f(k)),...,1} is equal to n, where f is the Collatz function.
a(n) <= 4^(n-1). - Robert G. Wilson v, Nov 16 2016
a(n) <= (4^(n-1)-1)/3 for n > 2. - Michael S. Branicky, Apr 08 2024
LINKS
EXAMPLE
MATHEMATICA
f[n_]:=n/2/; Mod[n, 2]==0; f[n_]:=3 n+1/; Mod[n, 2]==1; g[n_]:=Module[{i, p}, i=n; p=1; While[i>1, If[IntegerQ[Sqrt[i]], p=p+1]; i=f[i]]; p]; Do[k=1; While[g[k]!=m, k++]; Print[m, " ", k], {m, 1, 13}]
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Michel Lagneau, Nov 13 2016
EXTENSIONS
a(14)-a(15) from Robert G. Wilson v, Nov 16 2016
a(16)-a(18) from Michael S. Branicky, Apr 08 2024
STATUS
approved