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%I #20 Jun 26 2022 03:58:26
%S 1,2,6,4,19,6,28,24,45,10,98,12,79,94,120,16,201,18,238,164,171,22,
%T 436,120,229,234,426,28,695,30,496,352,369,370,1014,36,451,470,1068,
%U 40,1261,42,946,1020,639,46,1832,336
%N GCD-convolution of squares A000290 with themselves.
%H Danny Rorabaugh, <a href="/A033457/b033457.txt">Table of n, a(n) for n = 0..10000</a>
%F a(n-2) = Sum_{d|n, d<n} d^2*phi(n/d). - _Vladeta Jovovic_, Aug 27 2003
%t Table[Sum[d^2*EulerPhi[(n + 2)/d], {d, Most@ Divisors[n + 2]}], {n, 0, 47}] (* _Michael De Vlieger_, Mar 20 2015 *)
%o (Sage) sum([d^2*euler_phi(int((n+2)/d)) for d in range(1,n+2) if (n+2)%d==0]) # _Danny Rorabaugh_, Mar 20 2015
%Y Cf. A000010 (phi), A000290, A069097.
%K nonn,easy
%O 0,2
%A _N. J. A. Sloane_
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