A079477 - OEIS

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A079477

First prime after phi(prime(n)^2).

3, 7, 23, 43, 113, 157, 277, 347, 509, 821, 937, 1361, 1657, 1811, 2179, 2767, 3433, 3671, 4423, 4973, 5261, 6163, 6823, 7841, 9319, 10103, 10513, 11351, 11777, 12659, 16007, 17033, 18637, 19183, 22063, 22651, 24499, 26407, 27733, 29759, 31873, 32587, 36293

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

The sequence always increases.

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = A151800(A036689(n)). - Michel Marcus, Mar 15 2023

EXAMPLE

p_3=5, phi(5^2)=phi(25)=20, therefore a(3)=23

MAPLE

a:= n-> nextprime(2*binomial(ithprime(n), 2)):

seq(a(n), n=1..44); # Alois P. Heinz, Mar 15 2023

MATHEMATICA

Prime[1+PrimePi[EulerPhi[Prime[Range[41]]^2]]] (* T. D. Noe, Nov 15 2006 *)

PROG

(PARI) forprime (p=2, 200, print1(nextprime(eulerphi(p^2))", "))

CROSSREFS

Cf. A036689, A151800.

Sequence in context: A133434 A122870 A216816 * A014426 A054270 A058000

Adjacent sequences: A079474 A079475 A079476 * A079478 A079479 A079480

KEYWORD

nonn

AUTHOR

Jon Perry, Jan 15 2003

EXTENSIONS

Corrected by T. D. Noe, Nov 15 2006

STATUS

approved