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Search: id:A139096
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| A139096 |
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Infraperfect numbers: 2^(2p - 1) - 2^p, where p is A000043(n). |
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+0
4
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OFFSET
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1,1
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COMMENT
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Difference between n-th even perfect number and n-th even superperfect number A061652(n). Difference beetwen 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.
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LINKS
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O. E. Pol, Determinacion geometrica de los numeros primos y perfectos.
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FORMULA
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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) - A075398(n).
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EXAMPLE
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a(2)=24 because A000043(2)=3 then 2^(2*3 - 1) - 2^3 = 2^5 - 2^3 = 32 - 8 = 24.
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CROSSREFS
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Cf. A000396, A000668, A019279, A061652, A075398, A139306.
Sequence in context: A166947 A101952 A009535 this_sequence A111425 A013100 A013061
Adjacent sequences: A139093 A139094 A139095 this_sequence A139097 A139098 A139099
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KEYWORD
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nonn,more
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AUTHOR
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Omar E. Pol (info(AT)polprimos.com), Apr 22 2008
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