A292714 Composite numbers k such that phi(x) = psi(k)*phi(k) has no solution.
2197, 4934, 5386, 7606, 10774, 11434, 15212, 15214, 15634, 16294, 17146, 18134, 18374, 18994, 19466, 20134, 20362, 23194, 23451, 24051, 24874, 25526, 25934, 26326, 27411, 27561, 27994, 28486, 28561, 30034, 31334, 31366, 36748, 37834, 38074, 40694, 44054, 46234, 47494, 49834
Offset: 1
Keywords
Examples
4934 = 2*2467 is a term because psi(4934)*phi(4934) = (2^2 - 1)*(2467^2 - 1) = 2^3*3^3*137*617 is not a totient number (A002202).
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000
Programs
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PARI
is(k) = if(isprime(k), 0, my(f = factor(k)); !istotient(prod(i = 1, #f~, (f[i, 1]^2 - 1) * f[i, 1]^(2*f[i, 2] - 2)))); \\ Amiram Eldar, Dec 05 2024
Comments