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%I #8 Sep 27 2024 05:42:03
%S 1,7,155,2667,11180715,2863245995,45812722347,768614335330822827,
%T 886151997189943914116283202246716075,
%U 63853980869412035764931125821777872829435728032869035,4388012152856549445746584486819520216982214368341183846591146667,4824670384888174809315457708695329493801178769338122219111555681805105015467
%N M(M-1)/6, where M is Mersenne prime A000668(n).
%C Perfect number A000396(n) minus Mersenne prime A000668(n), divided by 3.
%C Terms from a(13) on have 313 or more digits and are not listed for that reason. - _R. J. Mathar_, May 11 2008
%H Omar E. Pol, <a href="http://www.polprimos.com">Determinacion geometrica de los numeros primos y perfectos</a>.
%F a(n) = A000668(n)*(A000668(n)-1)/6 = A139223(n)/6 = A139224(n)/3.
%F a(n) = (A000396(n)-A000668(n))/3.
%Y Cf. A000217, A000396, A000668, A036689, A139096, A139115, A139116, A139223, A139224, A139225, A139256, A139306.
%K nonn
%O 1,2
%A _Omar E. Pol_, May 10 2008
%E More terms from _R. J. Mathar_, May 11 2008