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%I M5337 #20 Jun 22 2017 10:58:50
%S 70,102,114,138,174,186,222,246,258,282,318,350,354,366,372,402,426,
%T 438,444,474,490,492,498,516,534,550,564,572,582,606,618,636,642,650,
%U 654,678,708,732,738,748,762,770,774,786,804,822,834,836,846,852,876,894
%N Impractical numbers: even abundant numbers (A173490) that are not practical(2) (A007620).
%D R. Honsberger, Mathematical Gems, M.A.A., 1973, p. 113.
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H T. D. Noe, <a href="/A007621/b007621.txt">Table of n, a(n) for n = 1..1000</a>
%H Robert G. Wilson v, <a href="/A007621/a007621.pdf">Letter to N. J. A. Sloane</a>, date unknown.
%t practicalQ[n_] := Module[{d = Divisors[n], c}, c = Rest[CoefficientList[Series[Product[1 + x^d[[i]], {i, Length[d]}], {x, 0, n}], x]]; Flatten[Position[c, 0]] == {} && c[[-1]] > 1]; Select[2*Range[500], DivisorSigma[1, #] > 2 # && ! practicalQ[#] &] (* _T. D. Noe_, Jun 25 2012 *)
%Y A173490 with A007620 removed. Cf. A035480.
%K nonn
%O 1,1
%A _N. J. A. Sloane_, _Mira Bernstein_, _Robert G. Wilson v_
%E More terms from _David W. Wilson_.
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