|
| |
|
|
A037176
|
|
Numbers n such that us(n) = number of primes <= n, where usigma(n) = sum of unitary divisors of n (A034448), us(n) is usigma(n)-n.
|
|
0
| |
|
|
1, 2, 56, 80, 85, 2527, 2569, 2723, 2807, 7864, 7976, 22941, 113488, 174449, 461403
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,2
|
|
|
PROG
| (PARI) us(n) = sumdiv(n, d, if(gcd(d, n/d)==1, d)); f(n)=s=0; for(x=1, n, if(isprime(x), s++)); s; for(n=1, 10^6, if(us(n)-n==f(n), print(n)))
|
|
|
CROSSREFS
| Sequence in context: A186886 A024029 A134501 * A045819 A193830 A196539
Adjacent sequences: A037173 A037174 A037175 * A037177 A037178 A037179
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Naohiro Nomoto (6284968128(AT)geocities.co.jp)
|
|
|
EXTENSIONS
| a(12) from Jason Earls (zevi_35711(AT)yahoo.com), Sep 06 2001
a(13) - a(15) from Nathaniel Johnston (nathaniel(AT)nathanieljohnston.com), Apr 29 2011
|
| |
|
|
