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A139224 M(M-1)/2, where M is Mersenne prime A000668(n). 7
3, 21, 465, 8001, 33542145, 8589737985, 137438167041, 2305843005992468481, 2658455991569831742348849606740148225, 191561942608236107294793377465333618488307184098607105 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Perfect number A000396(n) minus Mersenne prime A000668(n).
LINKS
Table of n, a(n) for n=1..10.
Omar E. Pol, Determinacion geometrica de los numeros primos y perfectos".
FORMULA
a(n)=A000668(n)*(A000668(n)-1)/2. Also a(n)=A000396(n)-A000668(n).
CROSSREFS
Cf. A000217, A000396, A000668, A036689, A139096, A139115, A139116, A139223, A139225, A139226, A139256, A139306.
Sequence in context: A120603 A336578 A285380 * A032469 A006927 A014375
Adjacent sequences: A139221 A139222 A139223 * A139225 A139226 A139227
KEYWORD
nonn
AUTHOR
Omar E. Pol, May 10 2008
EXTENSIONS
More terms from Max Alekseyev, Mar 09 2009
STATUS
approved

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Last modified May 20 13:41 EDT 2024. Contains 372715 sequences. (Running on oeis4.)