|
| |
|
|
A063752
|
|
Numbers n such that cototient(n) is a square.
|
|
2
| |
|
|
1, 2, 3, 5, 6, 7, 8, 11, 13, 17, 19, 21, 23, 24, 27, 28, 29, 31, 32, 37, 41, 43, 47, 53, 54, 59, 61, 67, 68, 69, 71, 73, 79, 83, 89, 96, 97, 101, 103, 107, 109, 112, 113, 124, 125, 127, 128, 131, 133, 137, 139, 141, 149, 151, 157, 163, 167, 173, 179, 181, 189, 191
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,2
|
|
|
LINKS
| Harry J. Smith, Table of n, a(n) for n=1,...,1000
|
|
|
FORMULA
| a(n) seems to be asymptotic to c*n*log(n) with c=1.07....(all primes are in the sequence since cototient(p)=1) - Benoit Cloitre (benoit7848c(AT)orange.fr), Sep 08 2002
|
|
|
PROG
| (PARI) j=[]; for(n=1, 400, x=n-eulerphi(n); if(issquare(x), j=concat(j, n))); j
(PARI) { n=0; for (m=1, 10^9, if (issquare(m - eulerphi(m)), write("b063752.txt", n++, " ", m); if (n==1000, break)) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Aug 29 2009]
|
|
|
CROSSREFS
| Cf. A051953.
Sequence in context: A140661 A063966 A123030 * A191893 A016741 A191167
Adjacent sequences: A063749 A063750 A063751 * A063753 A063754 A063755
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Jason Earls (zevi_35711(AT)yahoo.com), Aug 11 2001
|
| |
|
|
