A139226 M(M-1)/6, where M is Mersenne prime A000668(n).

1, 7, 155, 2667, 11180715, 2863245995, 45812722347, 768614335330822827, 886151997189943914116283202246716075, 63853980869412035764931125821777872829435728032869035, 4388012152856549445746584486819520216982214368341183846591146667, 4824670384888174809315457708695329493801178769338122219111555681805105015467

Offset

1,2

Comments

Perfect number A000396(n) minus Mersenne prime A000668(n), divided by 3.

Terms from a(13) on have 313 or more digits and are not listed for that reason. - R. J. Mathar, May 11 2008

Links

Table of n, a(n) for n=1..12.

Omar E. Pol, Determinacion geometrica de los numeros primos y perfectos".

Formula

a(n)=A000668(n)*(A000668(n)-1)/6 = A139223(n)/6 = A139224(n)/3. Also a(n)=(A000396(n)-A000668(n))/3.

Crossrefs

Cf. A000217, A000396, A000668, A036689, A139096, A139115, A139116, A139223, A139224, A139225, A139256, A139306.

Sequence in context: A141835 A111831 A288545 * A220367 A220311 A218449

Adjacent sequences: A139223 A139224 A139225 * A139227 A139228 A139229

Keyword

nonn

Author

Omar E. Pol, May 10 2008

Extensions

More terms from R. J. Mathar, May 11 2008

Status

approved