[seqfan] about A051532

[jean-paul allouche]

Dear all

A statement by T. D. Noe in A051532 gives a (seemingly indicated as
necessary) condition for n to occur in this sequence (look at "Formula").
Actually it sems that this condition is necessary *and* sufficient: this
seems to be a 1905 theorem by Dickson: see
http://www.ams.org/journals/tran/1905-006-02/S0002-9947-1905-1500706-2/S0002-9947-1905-1500706-2.pdf
(Theorem bottom on Page 200 and top on Page 201.)

Could someone better than me in group theory double check
the result and make the corresponding editing in the OEIS?

many thanks in advance
best wishes
jean-paul