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.

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

Author

Antti Karttunen, Mar 02 2018

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..65537
• Antti Karttunen, Scheme (Racket) program to compute this sequence

Crossrefs

Cf. A000203, A285721.

Cf. also A286594, A300228, A300234, A300237, A300238.

Programs

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));

Formula

a(1) = 1; for n > 1, a(n) = A285721(n,A000203(n)-1).