login
A339972
Odd part of phi(A019565(8*n)).
2
1, 3, 5, 15, 3, 9, 15, 45, 1, 3, 5, 15, 3, 9, 15, 45, 9, 27, 45, 135, 27, 81, 135, 405, 9, 27, 45, 135, 27, 81, 135, 405, 11, 33, 55, 165, 33, 99, 165, 495, 11, 33, 55, 165, 33, 99, 165, 495, 99, 297, 495, 1485, 297, 891, 1485, 4455, 99, 297, 495, 1485, 297, 891, 1485, 4455, 7, 21, 35, 105, 21, 63, 105, 315, 7, 21
OFFSET
0,2
COMMENTS
Compare also to the scatter plots of A339898 and A339901.
LINKS
FORMULA
If 16n = 2^e1 + 2^e2 + ... + 2^ek [e1 ... ek distinct], then a(n) = A057023(e1) * A057023(e2) * ... * A057023(ek).
a(n) = A339971(4*n) = A000265(A339821(4*n)) = A053575(A019565(8*n)).
PROG
(PARI)
A000265(n) = (n>>valuation(n, 2));
A339972(n) = { my(m=1, p=5); while(n>0, p = nextprime(1+p); if(n%2, m *= A000265(p-1)); n >>= 1); (m); };
CROSSREFS
Quadrisection of A339971.
Sequence in context: A118562 A273164 A317661 * A115043 A272255 A270688
KEYWORD
nonn,look
AUTHOR
Antti Karttunen, Dec 26 2020
STATUS
approved