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A181704
Numbers m=2^(t-1)*(2^t-5), where 2^t-5 is prime.
3
12, 88, 1888, 32128, 521728, 8378368, 34359083008, 549753192448, 2251799645913088, 9223372026117357568, 2361183241263023915008, 2596148429267413634121263069790208, 2722258935367507707522529418717050175488
OFFSET
1,1
COMMENTS
All these numbers are in A181595 because their abundance is 4, a proper divisor of m.
MATHEMATICA
Rest[2^(#-1) (2^#-5)&/@(Round[N[Log[#+5]/Log[2]]]&/@Select[Table[2^t-5, {t, 120}], PrimeQ])] (* Harvey P. Dale, Dec 16 2010 *)
KEYWORD
nonn
AUTHOR
Vladimir Shevelev, Nov 06 2010
EXTENSIONS
571728 replaced with 521728 by R. J. Mathar, Dec 05 2010
STATUS
approved