OFFSET
0,3
FORMULA
PROG
(PARI) A339820(n) = { my(m=1, p=1); while(n>0, p = nextprime(1+p); if(n%2, m *= (p-1)); n >>= 1); (m); };
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Dec 18 2020
STATUS
approved