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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

Table of n, a(n) for n=1..10.

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

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

Cf. A000396, A000668, A019279, A061652, A072868, A139306.

Sequence in context: A103624 A101952 A009535 * A111425 A013100 A013061

Adjacent sequences:  A139093 A139094 A139095 * A139097 A139098 A139099

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 June 25 07:53 EDT 2019. Contains 324347 sequences. (Running on oeis4.)