OFFSET
1,2
COMMENTS
An 11-smooth number is a number of the form 2^x*3^y*5^z*7^u*11^v (x,y,z,u,v) >= 0.
FORMULA
a(n) = Card{ k | A051038(k) <= n }
MATHEMATICA
Accumulate[Table[If[Max[FactorInteger[n][[;; , 1]]]<=11, 1, 0], {n, 120}]] (* Harvey P. Dale, Sep 02 2024 *)
PROG
(PARI) a(n)=sum(k=1, n, (k<4) || 13>vecmax(factor(k)~[1, ]))
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Benoit Cloitre, Jun 02 2002
STATUS
approved