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

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