A217619 a(n) = m/(12*n) where m is the least multiple of n that satisfies phi(m) = phi(m+6*n).
2, 2, 2, 2, 3, 2, 2, 2, 2, 3, 2, 2, 2, 2, 3, 2, 2, 2, 2, 3, 2, 2, 2, 2, 3, 2, 2, 2, 2, 3, 2, 2, 2, 2, 5, 2, 2, 2, 2, 3, 2, 2, 2, 2, 3, 2, 2, 2, 2, 3, 2, 2, 2, 2, 3, 2, 2, 2, 2, 3, 2, 2, 2, 2, 3, 2, 2, 2, 2, 5, 2, 2, 2, 2, 3, 2, 2, 2, 2, 3, 2, 2, 2, 2, 3, 2, 2
Offset: 1
Keywords
Examples
A179188(1)=24 is divisible by 1 and the quotient 24 when divided by 12 gives 2, so a(1)=2. A217139(1)=48 is divisible by 2 and the quotient 24 when divided by 12 gives 2, so a(2)=2. A217140(5)=36 and 36/12=3, so a(5)=3.
Links
- S. W. Graham, J. J. Holt and C. Pomerance, On the solutions to phi(n) = phi(n+k), Number Theory in Progress, K. Gyory, H. Iwaniec, and J. Urbanowicz, eds., vol. 2, de Gruyter, Berlin and New York, 1999, pp. 867-882.
Formula
a(n) = A217140(n)/12.
Comments