login
A300227
a(n) = number of steps in simple Euclidean algorithm for gcd(n,k) to reach the termination test n=k when starting with n = n and k = sigma(n)-1, with a(1) = 1.
6
1, 0, 0, 2, 0, 6, 0, 4, 3, 6, 0, 5, 0, 7, 9, 8, 0, 10, 0, 21, 12, 8, 0, 10, 5, 8, 6, 28, 0, 9, 0, 16, 9, 9, 14, 3, 0, 10, 9, 11, 0, 11, 0, 13, 11, 11, 0, 8, 7, 10, 10, 12, 0, 16, 10, 9, 10, 12, 0, 11, 0, 13, 11, 32, 10, 7, 0, 13, 13, 27, 0, 10, 0, 14, 8, 13, 11, 19, 0, 9, 15, 15, 0, 15, 13, 16, 11, 33, 0, 13, 12, 12, 11, 17, 27, 14, 0
OFFSET
1,4
FORMULA
a(1) = 1; for n > 1, a(n) = A285721(n,A000203(n)-1).
PROG
(PARI)
A285721(n, k) = if(n==k, 0, 1 + A285721(abs(n-k), min(n, k)));
A300227(n) = if(1==n, n, A285721(n, sigma(n)-1));
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Mar 02 2018
STATUS
approved