OFFSET
1,2
COMMENTS
a(n) is a generalization of the multiperfect numbers in A007691.
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..12857
Antti Karttunen, Data supplement: n, a(n) computed for n = 1..65537
FORMULA
a(multiperfect) = 1.
a(prime) = 2 as 1*phi(prime) + 1*sigma(prime) and 1+1 = 2.
For primes > 5, a(2*prime) = 4.
EXAMPLE
a(6) = 1 as 1*sigma(6) is a multiple of 6.
a(4) = 2 as 2*phi(4) + 0*sigma(4) = 4. - Example added by Antti Karttunen, Feb 24 2020
a(14) = 4 as 3*phi(14) + 1*sigma(14) = 3*6 + 24 = 3*14, where 3+1 = 4.
PROG
(PARI) A094701(n) = { my(x=eulerphi(n), y=sigma(n)); for(s=1, oo, for(t=0, s, if(!(((t*x)+((s-t)*y))%n), return(s)))); }; \\ Antti Karttunen, Feb 24 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
Walter Nissen, May 20 2004
EXTENSIONS
Name clarified by Antti Karttunen, Feb 24 2020
STATUS
approved