A110192 Least k>n such that phi(k)=2*phi(n), where phi is Euler's totient function.

3, 3, 5, 5, 15, 8, 13, 15, 13, 15, 25, 15, 35, 21, 17, 17, 51, 21, 37, 32, 35, 25, 69, 32, 41, 35, 37, 35, 87, 32, 61, 51, 41, 51, 65, 39, 73, 57, 65, 51, 123, 45, 129, 55, 65, 69, 141, 51, 129, 55, 85, 65, 159, 57, 123, 65, 73, 87, 177, 64, 143, 77, 73, 85, 97, 75, 161, 85

Offset

1,1

Links

Table of n, a(n) for n=1..68.

Formula

a(n)=A110179(n)+n

Mathematica

Table[k=n+1; e=EulerPhi[n]; While[EulerPhi[k] != 2e, k++ ]; k, {n, 100}]

Crossrefs

Sequence in context: A325679 A147198 A147048 * A014414 A087745 A087756

Adjacent sequences: A110189 A110190 A110191 * A110193 A110194 A110195

Keyword

nonn

Author

T. D. Noe, Jul 15 2005

Status

approved