|
| |
|
|
A064439
|
|
Numbers n such that sigma(n)-n-1 = pi(n).
|
|
0
| |
|
|
4, 55, 65, 95, 125, 145, 155, 185, 205, 2779, 2863, 55297, 174691, 174779, 487903, 1301989, 1302457
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,1
|
|
|
PROG
| (PARI) sig(n) = sigma(n)-n-1; pi(x, c=0) = forprime(p=2, x, c++); c for(n=1, 10^8, if(sig(n)==pi(n), print(n)))
(PARI) { n=0; for (m=1, 10^9, if ((sigma(m) - m - 1)==primepi(m), write("b064439.txt", n++, " ", m); if (n==100, break)) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Sep 14 2009]
|
|
|
CROSSREFS
| Cf. A000720, A048050.
Sequence in context: A140604 A048371 A077658 * A133218 A190441 A151576
Adjacent sequences: A064436 A064437 A064438 * A064440 A064441 A064442
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Jason Earls (zevi_35711(AT)yahoo.com), Oct 01 2001
|
|
|
EXTENSIONS
| More terms from Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Oct 05 2001. No further term < 800000.
a(16) - a(17) from Harry J. Smith (hjsmithh(AT)sbcglobal.net), Sep 14 2009
|
| |
|
|
