A049454 a(n) = 1 + Sum_{i=1..n} phi(i)^2.

1, 2, 3, 7, 11, 27, 31, 67, 83, 119, 135, 235, 251, 395, 431, 495, 559, 815, 851, 1175, 1239, 1383, 1483, 1967, 2031, 2431, 2575, 2899, 3043, 3827, 3891, 4791, 5047, 5447, 5703, 6279, 6423, 7719, 8043, 8619, 8875, 10475, 10619, 12383

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn

Links

• Harvey P. Dale, Table of n, a(n) for n = 0..1000

Crossrefs

Cf. A000010 (phi), A005728, A057434, A127473.

Programs

Mathematica

Table[1+Sum[EulerPhi[i]^2,{i,n}],{n,0,50}] (* Harvey P. Dale, Mar 21 2020 *)
Join[{1}, 1 + Accumulate[EulerPhi[Range[45]]^2]] (* Amiram Eldar, Dec 01 2024 *)

PARI

a(n) = 1 + sum(i=1, n, eulerphi(i)^2); \\ Michel Marcus, Mar 07 2020

Formula

a(n) = A057434(n) + 1 for n >= 1. - Amiram Eldar, Dec 01 2024