|
|
A159687
|
|
Number of strong primes < 10^n.
|
|
0
|
|
|
0, 10, 73, 574, 4543, 37723, 320991, 2796946, 24758534, 222126290, 2014200162
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
The number of strong primes < n ~ sum of strong primes < sqrt(n). The number of strong primes < 10^11 = 2014200162 and the sum of strong primes < 10^5.5 = 1972716560, for an error of 0.0206.
|
|
LINKS
|
|
|
FORMULA
|
Given 3 consecutive primes p1,p2,p3, p2 is a strong prime if p2 > (p1+p2)/2.
Or, primes that are greater than the arithmetic mean of their immediate surrounding primes.
|
|
EXAMPLE
|
The strong primes < 10^2 are 11, 17, 29, 37, 41, 59, 67, 71, 79, 97. These add up to 10 which is the second term in the sequence.
|
|
PROG
|
(Other) See the link for Gcc programs that count and sum these primes.
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,more
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|