OFFSET
0,1
LINKS
Steven R. Finch, Triple-Free Sets of Integers [From Steven Finch, Apr 20 2019]
Julien Cassaigne and Paul Zimmermann, Numerical Evaluation of the Strongly Triple-Free Constant (1996). [From Steven Finch, Feb 25 2009]
Julien Cassaigne and Paul Zimmermann, Numerical Evaluation of the Strongly Triple-Free Constant (pdf file, 1996).
Eric Weisstein's World of Mathematics, Triple-Free Set
EXAMPLE
0.613475269...
0.6134752692022344160180416638... - Steven Finch, Feb 25 2009
MATHEMATICA
f[k_, n_]:=1+Floor[FullSimplify[Log[n/3^k]/Log[2]]]; g[n_]:=Floor[FullSimplify[Log[n]/Log[3]]]; peven[n_]:=Sum[Quotient[f[k, n]+Mod[k+1, 2], 2], {k, 0, g[n]}]; podd[n_]:=Sum[Quotient[f[k, n]+Mod[k, 2], 2], {k, 0, g[n]}]; p[n_]:=Max[peven[n], podd[n]]; v[1]=1; j=1; k=1; n=4001; For[k=2, k=n, k++, If[2*v[k-j]<3^j, v[k]=2*v[k-j], {v[k]=3^j, j++}]]; Sum[p[v[n]]*(1/v[n]-1/v[n+1]), {n, 1, 4000}]/3 (* Steven Finch, Feb 25 2009 *)
CROSSREFS
KEYWORD
AUTHOR
Eric W. Weisstein, Jul 15 2003
EXTENSIONS
More terms from Steven Finch, Feb 25 2009
STATUS
approved