A079476 First prime greater than or equal to phi(n^2).

2, 2, 7, 11, 23, 13, 43, 37, 59, 41, 113, 53, 157, 89, 127, 131, 277, 109, 347, 163, 257, 223, 509, 193, 503, 313, 487, 337, 821, 241, 937, 521, 661, 547, 853, 433, 1361, 691, 937, 641, 1657, 509, 1811, 881, 1087, 1013, 2179, 769, 2063, 1009, 1637, 1249, 2767

Offset: 1

Author

Jon Perry, Jan 15 2003

Keywords

• nonn
• look

Comments

The sequence generally goes up,down,up,down...

Examples

			phi(3^2)=phi(9)=6, therefore a(3)=7.
		

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A002618, A007918.

Programs

Maple

map(t -> nextprime(numtheory:-phi(t^2)-1), [$1..100]); # Robert Israel, Oct 25 2017

Mathematica

Array[If[PrimeQ@ #, #, NextPrime@ #] &@ EulerPhi[#^2] &, 53] (* Michael De Vlieger, Oct 25 2017 *)

PARI

for (n=1,100, print1(nextprime(eulerphi(n^2))","))

Formula

a(n) = A007918(A002618(n)). - Robert Israel, Oct 25 2017

Extensions

Corrected by Robert Israel, Oct 25 2017