|
Search: id:A132793
|
|
|
| A132793 |
|
Numbers n such that sigma(phi(n))-phi(n)=phi(sigma(n)-n). |
|
+0
2
|
|
| 1, 3, 70, 138, 792, 924, 1692, 1932, 2124, 2250, 2988, 3852, 30936, 112644, 189252, 240120, 261660, 263928, 338760, 364308, 379470, 390432, 504216, 529110, 785568, 862290, 917700, 979596, 1022310, 1124220, 1404270, 1434072, 2004372, 2526000
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
COMMENT
|
Used sigma(n)-n, namely the sum of proper divisors.
|
|
MAPLE
|
with(numtheory); P:=proc(n) local i, j, k; for i from 1 by 1 to n do j:=sigma(phi(i))-phi(i); k:=phi(sigma(i)-i); if j=k then print(i); fi; od; end: P(150000);
|
|
PROGRAM
|
(PARI) isA132793(n)={ if( sigma(eulerphi(n))-eulerphi(n) == eulerphi(sigma(n)-n), 1, 0 ) ; } { for(n=2, 6000000, if(isA132793(n), print(n) ; ) ; ) ; } - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 11 2007
|
|
CROSSREFS
|
Cf. A000010, A000203, A001229, A018784, A033632, A132794.
Sequence in context: A012096 A012074 A037109 this_sequence A061173 A000282 A140048
Adjacent sequences: A132790 A132791 A132792 this_sequence A132794 A132795 A132796
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Paolo P. Lava & Giorgio Balzarotti (ppl(AT)spl.at), Aug 31 2007
|
|
EXTENSIONS
|
More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 11 2007
|
|
|
Search completed in 0.002 seconds
|
