login
Pseudoperfect numbers (A005835) that are not practical (second definition, A007620).
2

%I #13 Jan 04 2020 09:07:28

%S 102,114,138,174,186,222,246,258,282,318,350,354,366,372,402,426,438,

%T 444,474,490,492,498,516,534,550,564,572,582,606,618,636,642,650,654,

%U 678,708,732,738,748,762,770,774,786,804,822,834,846,852,876,894,906,910,940,942,945,948,954,978,996,1002

%N Pseudoperfect numbers (A005835) that are not practical (second definition, A007620).

%H Amiram Eldar, <a href="/A035480/b035480.txt">Table of n, a(n) for n = 1..1000</a>

%t Cases[ A005835, q_/;(Count[ CoefficientList[ Series[ Times@@( (1+z^#)& /@ Divisors[ q ] ), {z, 0, q} ], z ], 0 ]>0) ]

%Y Numbers in A005835 but not in A007620.

%Y Cf. A007621.

%K nonn

%O 1,1

%A _Wouter Meeussen_

%E Corrected by _David W. Wilson_.