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A110192 Least k>n such that phi(k)=2*phi(n), where phi is Euler's totient function. 0
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified May 6 02:09 EDT 2021. Contains 343579 sequences. (Running on oeis4.)