login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A070880 Look at all 2^(n-1)-1 nonempty subsets S of {1, 2, ..., n-1}; a(n) gives number of such S with property that it is impossible to partition n into parts from S such that each s in S is used at least once. 3
0, 0, 1, 3, 10, 22, 52, 110, 234, 482, 987, 1997, 4035, 8113, 16288, 32644, 65388, 130886, 261922, 524013, 1048250, 2096752, 4193831, 8388033, 16776543, 33553621, 67107918, 134216596, 268434139, 536869354, 1073740011, 2147481510, 4294964833, 8589931699 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..100

FORMULA

a(n) = 2^(n-1) - A088314(n). - Charlie Neder, Feb 08 2019

EXAMPLE

a(4)=3 because there are three different subsets S of {1,2,3} satisfying the condition: {3}, {2,3} & {1,2,3}. For the other subsets S, such as {1,2}, there is a partition of 4 which uses them all (such as 4 = 1+1+2).

CROSSREFS

Cf. A088314, A088528.

Sequence in context: A294414 A299336 A222629 * A321335 A171686 A027164

Adjacent sequences: A070877 A070878 A070879 * A070881 A070882 A070883

KEYWORD

easy,nonn

AUTHOR

Naohiro Nomoto, Nov 16 2003

EXTENSIONS

Edited by N. J. A. Sloane, Sep 09 2017

a(20)-a(34) from Alois P. Heinz, Feb 08 2019

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 27 21:49 EST 2023. Contains 359849 sequences. (Running on oeis4.)