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A065604 a(n) = smallest k satisfying the equation phi(k) = phi(k-1) + phi(k-2) and having just n prime factors. 0
3, 1037, 619697, 218688017, 32617225577 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..5.

EXAMPLE

a(1) = 3 which is prime and is the first term in A065557, a(2) = 1037 = 17*61 which is the first term in A065572, a(3) = 619697=13*73*653

MATHEMATICA

a = Table[0, {4}]; x = y = 1; Do[ z = EulerPhi[n]; If[z == x + y, If[l = Length[ FactorInteger[ n]]; a[[l]] == 0, a[[l]] = n; Print[n]]]; x = y; y = z, {n, 3, 10^7 } ]; a

CROSSREFS

Cf. A065557 and A065572.

Sequence in context: A152505 A139301 A004803 * A062612 A096082 A274994

Adjacent sequences:  A065601 A065602 A065603 * A065605 A065606 A065607

KEYWORD

hard,nonn

AUTHOR

Robert G. Wilson v, Dec 01 2001

EXTENSIONS

a(5) from Donovan Johnson, Feb 05 2010

STATUS

approved

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Last modified September 19 15:37 EDT 2021. Contains 347564 sequences. (Running on oeis4.)