OFFSET
0,3
COMMENTS
For n > 0, a(n) gives the length of primorial base expansion of n. Also, after zero, each value n occurs A061720(n-1) times. - Antti Karttunen, Oct 19 2019
LINKS
FORMULA
MAPLE
A235224 := proc(n)
local k;
if n = 0 then
0;
else
for k from 0 do
if A002110(k-1) > n then
return k-1 ;
end if;
end do:
end if;
end proc: # R. J. Mathar, Apr 19 2021
MATHEMATICA
primorial[n_] := Times @@ Prime[Range[n]];
a[n_] := TakeWhile[primorial /@ Range[0, n], # <= n &] // Length;
Table[a[n], {n, 0, 100}] (* Jean-François Alcover, Oct 27 2021 *)
PROG
(Haskell)
a235224 n = length $ takeWhile (<= n) a002110_list
(PARI) A235224(n) = { my(s=0, p=2); while(n, s++; n = n\p; p = nextprime(1+p)); (s); }; \\ Antti Karttunen, Oct 19 2019
(PARI) A235224(n, p=2) = if(!n, n, if(n<p, 1, 1+A235224(n\p, nextprime(p+1)))); \\ (Recursive implementation) - Antti Karttunen, Oct 19 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Jan 05 2014
EXTENSIONS
Name corrected to match the data by Antti Karttunen, Oct 19 2019
STATUS
approved