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A139226 M(M-1)/6, where M is Mersenne prime A000668(n). 5
1, 7, 155, 2667, 11180715, 2863245995, 45812722347, 768614335330822827, 886151997189943914116283202246716075, 63853980869412035764931125821777872829435728032869035, 4388012152856549445746584486819520216982214368341183846591146667, 4824670384888174809315457708695329493801178769338122219111555681805105015467 (list; graph; refs; listen; history; text; internal format)
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

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Last modified June 20 10:07 EDT 2021. Contains 345162 sequences. (Running on oeis4.)