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A139096 Infraperfect numbers: 2^(2p - 1) - 2^p, where p is A000043(n). 2
4, 24, 480, 8064, 33546240, 8589803520, 137438429184, 2305843007066210304, 2658455991569831743501771111346995200, 191561942608236107294793377774818628309652252823388160 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Difference between n-th even perfect number and n-th even superperfect number A061652(n). Difference between n-th ultraperfect number A139306(n) and n-th Mersenne prime A000668(n), minus 1. Also, difference between n-th perfect number A000396(n) and n-th superperfect number A019279(n), if there are no odd perfect and superperfect numbers.
LINKS
FORMULA
a(n) = 2^(2*A000043(n) - 1) - 2^A000043(n) = A139306(n) - 2^A000043(n) = A139306(n) - A000668(n) - 1 = A139306(n) - (A000668(n)+1) = A139306(n) - 2*A061652(n) = A139306(n) - A072868(n).
EXAMPLE
a(2)=24 because A000043(2)=3 then 2^(2*3 - 1) - 2^3 = 2^5 - 2^3 = 32 - 8 = 24.
CROSSREFS
Sequence in context: A103624 A101952 A009535 * A111425 A013100 A013061
KEYWORD
nonn
AUTHOR
Omar E. Pol, Apr 22 2008
EXTENSIONS
More terms from R. J. Mathar, Feb 05 2010
STATUS
approved

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Last modified February 28 21:38 EST 2024. Contains 370400 sequences. (Running on oeis4.)