login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A228868 Sum of all numbers n>=2 such that in their Fermi-Dirac representation every A050376-factor does not exceed A050376(n). 1
2, 11, 59, 359, 2879, 28799, 345599, 4838399, 82252799, 1480550399, 29611007999, 710664191999, 18477268991999, 554318069759999, 17738178232319999, 674050772828159999, 28310132458782719999, 1245645828186439679999, 59790999752949104639999 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Or, the same, diminished on 1 the sum of Fermi-Dirac divisors of the number prod{i=1,...,n} A050376(i). Note that the sequence of the first differences 2, 9, 48, 300,... lists sums of all numbers such that the maximal A050376-factor in their Fermi-Dirac representation is A050376(n). Note also that the average of numbers n>=2 with A050376-factors not exceeding A050376(n) is a(n)/(2^n-1). Thus the sequence of such averages begins 2, 11/3, 59/7, 359/15,...

Prime terms are 2, 11, 59, 359, 2879, 345599, 4838399,...

LINKS

Peter J. C. Moses, Table of n, a(n) for n = 1..100

FORMULA

a(n) = prod{i=1,...,n}(A050376(i)+1) - 1.

EXAMPLE

a(3) = 2 + 3 + 2*3 = 11.

CROSSREFS

Cf. A050376.

Sequence in context: A054564 A280674 A139172 * A290116 A251180 A286194

Adjacent sequences:  A228865 A228866 A228867 * A228869 A228870 A228871

KEYWORD

nonn

AUTHOR

Vladimir Shevelev and Peter J. C. Moses, Sep 06 2013

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 24 02:31 EDT 2021. Contains 346270 sequences. (Running on oeis4.)