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A107656 Numbers n such that prime(n)=d(n)*phi(n)+1, where d(n) is number of positive divisors of n. 0
1, 2, 3, 4, 652245 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

There is no further term up to 5*10^7.

LINKS

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

EXAMPLE

652245 is in the sequence because prime(652245)=d(652245)*phi(652245)+1.

MATHEMATICA

Do[If[Prime[n] == DivisorSigma[0, n]*EulerPhi[n] + 1, Print[n]], {n, 50000000}]

CROSSREFS

Cf. A104905, A107657.

Sequence in context: A228311 A258107 A307256 * A024595 A144804 A118308

Adjacent sequences:  A107653 A107654 A107655 * A107657 A107658 A107659

KEYWORD

more,nonn

AUTHOR

Farideh Firoozbakht, Jun 06 2005

STATUS

approved

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Last modified May 19 20:41 EDT 2019. Contains 323410 sequences. (Running on oeis4.)