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%I #13 Jun 22 2021 16:33:41
%S 2,3,4,32,58,133,221,377,407,472,1241,1978,7232,13181,13952,15323,
%T 15409,17362,22328,32048,44215,46192,46498,46975,49228,73169,74498,
%U 128723,177305,241828,244352,297477,306835,417728,450023,455555,484942,640729,693259,707881,803509
%N Numbers m such that sigma(m+1)+sigma(m-1) = 5*phi(m).
%t Select[Range[804000],DivisorSigma[1,#+1]+DivisorSigma[1,#-1] == 5*EulerPhi[ #]&] (* _Harvey P. Dale_, Jun 22 2021 *)
%o (PARI) isok(m) = (m>1) && (sigma(m+1)+sigma(m-1) == 5*eulerphi(m)); \\ _Michel Marcus_, Feb 17 2021
%Y Cf. A000010, A000203, A067243.
%K easy,nonn
%O 1,1
%A _Benoit Cloitre_, Feb 20 2002
%E More terms from _Michel Marcus_, Feb 17 2021
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