A366079 Perfect squares in A005728.

1, 81, 121, 361, 1352569, 2140369, 6416089, 9186961, 30261001, 108056025, 820765201, 2331248089, 170938421809, 8189950752481, 8870860603201, 33527956250889, 136943052939289, 149526943190641, 4953581020385761, 509672946670475329, 578899033007097609, 2043000477545048329

Offset: 1

Author

Stuart E Anderson, Sep 28 2023

Keywords

• nonn

Examples

			a(3) = 361 because A005728(34) = 361 and 361 is 19 squared.
		

Crossrefs

Cf. A000290, A005728.

Programs

PARI

f(n)=1+sum(k=1, n, eulerphi(k)); \\ A005728
select(x->issquare(x), apply(f, [0..10^5])) \\ Michel Marcus, Sep 28 2023

Extensions

a(11)-a(12) from Michel Marcus, Sep 28 2023

a(13)-a(22) from Hugo Pfoertner, Sep 28 2023