A181704 Numbers m=2^(t-1)*(2^t-5), where 2^t-5 is prime.

12, 88, 1888, 32128, 521728, 8378368, 34359083008, 549753192448, 2251799645913088, 9223372026117357568, 2361183241263023915008, 2596148429267413634121263069790208, 2722258935367507707522529418717050175488

Offset: 1

Author

Vladimir Shevelev, Nov 06 2010

Keywords

• nonn

Comments

All these numbers are in A181595 because their abundance is 4, a proper divisor of m.

Crossrefs

Cf. A059608, A156560, A181595, A181701, A000396, A181703, A045769

Programs

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 *)

Extensions

571728 replaced with 521728 by R. J. Mathar, Dec 05 2010