|
|
A234422
|
|
Number of primes <= 123...n.
|
|
0
|
|
|
0, 5, 30, 202, 1474, 11601, 95360, 809227, 7027260, 556442057, 46063874346, 3930144647471, 342720306370180, 30384643585371049, 2728974793135786013, 247673123284120245960, 22671892206713857205404
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
|
|
FORMULA
|
|
|
EXAMPLE
|
There are 1474 primes <= 12345 so a(5) = 1474.
|
|
MATHEMATICA
|
PrimePi[Table[FromDigits[Flatten[IntegerDigits[Range[n]]]], {n, 12}]] (* Alonso del Arte, Dec 25 2013 *)
|
|
PROG
|
(Python)
def Num(x):
..num = ''
..for n in range(x):
....num += str(n+1)
..return num
from sympy import primepi
x = 1
while x < 10:
..print(primepi(int(Num(x))), end=', ')
..x += 1
(PARI) s=""; for(n=1, 20, s=concat(s, n); print1(primepi(eval(s)), ", ")) \\ Derek Orr, Apr 05 2015
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,base,hard,more
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|